PAPERS

ON SUBJECTS CONNECTED WITH

THE DUTIES

OF TUE

CORPS OF ROYAL ENGINEERS.

CONTRIBUTED BY

OFFICERS OF THE ROYAL ENGINEERS

AND

EAST INDIAN ENGINEERS.

NEW SERIES.

VOL X.

PRINTED BY W. P. JACKSON, WOOLWJCJ!.

1861.

PREFACE.

This volume contains some information relative to the effects of missiles

fired from rifled guns against brickwork, and the Report on the Experi•

ments made by the Prussians at J uliers shews their capability of breaching

walls hidden from view, without requiring the enormous amount of

ammunition employed in destroying the independent wall built at Woolwich

in 1821 ; but we require proofs of their effects in breaching works more

thoroughly protected, and placed so that they would strike them obliquely,

and with much diminished velocity, before we can arrive at any satisfactory

conclusions.

There are now so many volumes of the Professional Papers that an Index is much wanted to facilitate reference to them ; I have therefore

prepared an alphabetical list of the subjects of the Papers contained in the

volumes published since the index was printed in the 8th Vol. of the

Quarto Series, which I trust will be found more convenient than a more

lengthy index of contents; and spaces have been left to allow of additions

being made to it on the publication of new volumes.

P. J. BAINBRIGGE,

Lieut. Colonel, Royal Engineers,

Editor.

CONTENTS.

P.1per

I. ;\Iemoranclum on the increased power of Breaching to be

obtained by the use of Rifled Ordnance; by General Sir John Burgoyne, Bart., G.C.B., &c ............. .

II. On a proposed method of constructing Fire-proof Brick• nrc:hed Floors, devoid of any lateral thrust, and ,vith.

Page

out the use of tie-rods; by Captain Fowke, R.E.... 8

III. On the Form of the Voussoirs of a ConYergent Arch or Vault; by the Rev. John F. Twisden, l\I.A., Professor

of )Iathematics in the Staff College; communicated

by Lieutenant Home, R.E. . . . . . . . . . . . . . . . . . . . . . . . 11

IV. Notes upon the Construction of Builclings at Gibraltar with 'l'apia; compiled by Henry C. Jago, Clerk of

Works, R.E.D.; forwarded by Col. Stehelin, C.R.E., Gibraltar . . . . . . .. . .. • . . . . . . . . . . . . . . . • .. . .. . . . . . 25

V. Account of the Operation of Blasting ·with large charges at the Quarries at Holyhead in November, 1860; by

Colonel Hamilton, R.E. . . . . . . . . . . . . . . . . . . . . . . . . . 28

VI. J om·nal and Reports of tbe Operations of the Royal Engineers at the Siege of Jhansi; by the late Lieut. Colonel Fenwick and Major Edwards, R.E...... 33

VII. Report on two Bridges constructecl over the Gogra and Chowka Rivers; by Lieutenant Harrison, R.E. . . . . . 38

VIII. J oumal of the Operations at the Siege of Ahwah; by Captain Cumberland, R.E........................ 41

IX. Reports on the Engineering Operations during the Defence of Lncknow in 1857; by Major General Sir

J . Inglis, K.C.B, and other officers.... ... .. .. .. . 48

II

11

I l

, i.

l' :ip •r

X. Rcports on the Engineering Operations at the Sieg(' of Lucknow in l\Iarch, 185S i by Major General Sir H. Napier, K.C.B., Colonel Harness, C.B., ancl Lieutenant Colonel Lennox, R.E . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

XI. Report on the result of investigations on the Application of Electricity to the Explosion of Gw1powclcr; by Professor ,Vheatstone, F.R.S., and 1\1r. Abel, Chemist to the War Department . . . . . . . . . • . . . . . . . . . . . . . 89

XII. On the Destruction of Bridges ; by General Sir John Bw·goyne, Bart., G.C.B., &c........ . . . . . . . . . . . . 116

XIII. A Lunar Tide in Lake Michigan demonstrated by Lieut. Col. J. Graham, United States Topographical Engineers; communicated by Colonel Nelson, R.E.. 121

XIV. Notes on the Construction of Earth-works in Fortifica .. tions; by Major Gallwey and Lieutenant Innes, R.E. 126

XV. Ou the practical details of Photo-zincography, as applied at the Ordnance Survey Office, Southampton; by Colonel Sir Henry James, R.E., F.R.S., &c........ 129

XVI. Account of the Manfacture of a New Cement invented by Captain H. Scott, lt.E. . . . . . . . . . . . . . . . . . • . . . . • 132

XVII. Report on the Siege Operations carried on at Juliers in September, 1860, for the :instruction of the Prussian Army, especially with reference to the effects of Rifled Guns; by Lieutenant Colonel Ross, R.E., accompanied by Extracts from a Report on the same subject by Captain Giese, Prussian Royal Engineers, translated by Major General Hamilton, C.B . . . . . . . • 16 9

Index to the Professional Papers published since 1846.. i.

I

I

No.of P;qier.

LIST OF PLATES.

Sl'BJEC'T OF TUE PAPER,

I. Breaching a Tower at Eastbow·ne .. ......... .

H. Fire-proof Floors ................. .

Ill. Forms of Voussoii·s of an Arch ................. .

,-. Blasting at Holyhead ......................... .

\'I, Account of the Siege of Jhansi ................. .

l X. Operations at Lucknow ......................... .

XI. Abel's Fuzcs for Mines and Ordnance ........... .

XII. Bridge of St. Martino near Magenta ............. .

X \'I, Oven for the l\fannfacturc of Cement ............. .

X\"JI. Sicge Operations at J' uliers . ......... , ........ .

No. or Opp!>sit1 Pfate1. to Pa::;e

2 6

10

2 24

32

36

SS

114

120

158

2 last page.

I

PROFESSIONAL PAPERS.

PAPER I.

llEMORANDtTM ON TllE INCREASED POWER OF BREACHING TO BE Ol3TAINED

BY TIIE USE OF RIFLED ORDNANCE.

BY GENERAL SIR JOHN BURGOYNE, BART., O.C.B., &c.

The capability of effecting a breach by artillery, with the smooth bore and spherical projectiles, was rapidly reduced with increasing ranges; which diminished the Yelocity of the shot and the precision of the fire.

This imperfection may, for all practical purposes, be said to be entirely re­moved by t.he introduction of rifled ordnance.

Up to a l'ange of 1,000 yards, (and probably fmther trials will cany it some hundreds of yards beyond,) it has been ascertained to giYe the v,docity and pre­cision of pl'actice required to effect breaches, with a small increMe of the means necessary for the purpose at much shorter ranges ; whereas with the spherical missiles 600 or i00 yards may be deemed their utmost practical limits.

In addition to these advantages of retaining their velocity and their accuracy of fire, they have that of being much lighter for transport, (that is, the guns; for the weight of the missiles remains the same); a quality of peculiar value where the pieces may have to be conYeyed through trenches to close positions; and of requiring smaller charges of powder, which not only lessens the expendi­ture of ammunition, but renders the explosions less injurious to their own batteries; their shells also are capable of containing far more powder, to act as mines within the mass penetrated.

And yet there are drawbacks to the practical benefit deriYed from some of these items of superiority; viz.,

1. It is only works that have always been considered avowedly defecth·e thnt are subject to be breached at all, at any influential parts, from a distance; the rule being that all escarps should be well cow•rcd, and not lfo l>le to be brcacheil

A

2 ON THE INCREASED POWER OF BREACHING wrrn RIFLED ORDNANCE.

except from the opposite sido of the ditch,_ at whic~ . short distan~e the missile from the smooth bore gun has every reqmnd precrn,100, ancl havrng a greater initial velocity, will strike e,•en a harder blow than that from the rifled gun.

2. As regai:ds the shellsi they are not the missiles which 1!1ake the main :impression, and can only at best sonlllwhat accelerate t_he comvlehon of a breach; and it may be doubtful whether they arc of much avnil even to that extent, con­sideriJ1 ..... the uncertainty of the fuzcs in such service.

In c~nsidering the operation of effecting a breach, a distinction must be dra:wn as to the nabue and cll'cumstances of the wall, that is, whether it be an escru·p wall, with counterforts or buttresses, and 11crhaps arched in the manner called technically en decharge, and backed by solid earth, or whether it be isolated, like Carnot walls, towers, blockhouses, caponnieres or magazines, the force required to make a practicable breach in the former being far greater than that which will destroy the latter.

The following are some interesting details, extracted f.l'Om the Report of the Ordnance Select Committee on experiments made in August, 1860, with Armstrong's rifled guns against a condemned ~Iartello tower on the coast of Sussex.

" The Tower in question (No. 71) was built in the year 1804. It is of brick1

able to accommodate 20 men, with magazine s1mce for 80 barrels or 70 cases of powder. Like all the Martello Towers on this part of the coast, it is designed for one gun. The wall on the side fired at is 7 feet 6 inches thick at the le,·el of the ground, and 5 feet 9 inches at the spring of the vault, which is 19 feet from the ground. It is 31 feet 6 inches high, but receives considerable support, at 12 feet aboYe the ground, from the joists of the floor, which radiate from a central pillar, and abut against it. To a certain extent, also, the basement floor, at 2¼ feet abo,e the ground, may be regarded as a support. In appear­ance, the Tower was perfectly sound, the brickwork having been protected by a coating of plaster. The parapet, 5½ feet high and 5 feet thick, was coped with Bramley-fall stone, in blocks containi11g 7 or 8 cubic feet; ri. step 2 feet high, row1d the interior, served the double purpose of a banquette and of a support for the front racers of a rear-ph·ot traversing platform tuxning the entire circle. The racer itself was laid on granite cuxb-stones of about half-a-ton weight each. Thus a great solidity characterised the whole structure. The roof was formed of a bomb-proof vault, su111101·ted in the centre by a pillar 4 feet in diameter, turned in three cotu·ses of bricks, and stu·mounted by an equal thickness of ordinary brickwork, giviug altogether about 5 feet of masonry o,er the crown of the arch. The diameter of the whole at the top was 40 feet, and nearly 46 feet at the bottom. (See Plan).

" A broad black line was marked horizontally round the land side of the Tower, at 9 feet from the ground, and three similar vertical lines were marked on the face fired at. As a fUTther assistance to the record, every tenth com·se of bricks was numbered, in conspicuous figm·es, in four vertical rows,

" The spot cho~en for the position of the battery was a slightly-rising ground beyond the tu~"Ilpike-road from Eastbourne to Pevensey, on Hoisey Farm, and 1,032 yards distant from the Tower. Here, by an arrangement with the pro-

ON THE INCREASED POWER OF BREACHING WITH RIFLED ORDNANCE, 3

prietori a sufficient spnce was enclosed, and three platforms laid, on which the three following Armstrong breech-loading guns w·ere mounted:-

1. 82-Pouncler of 6 inches calibre. Charge for shot, 10 lbs.; for shells, 9 lbs.• 2. 7-inch Howitzer, throwing 100-pounder shells. Charge 9 lbs. 3. 40-Pounder of 4·75 inches calibre, No. 101. Charge, 5 lbs. The fire was opened at 8 a.m., on the_ morning of August 7, 1860, com­

mencing with solid shot from the 40-pounder and SO-pounder, and plugged shells from the 100-po,mder. 12 rounds were fired, of which 11 took effect.t

11 The brickwork was cracked through by the first six shots, and three or four com·ses were very slightly, but perce1ltibly started inwards. Thi.s was the only effect visible inside the tower, except where the seventh shot had penetrated. The cracks were very fine, scarcely traceable, but extended in two or three irregular lines from three feet above the floor to the spring of the arch, and seem to have been produced by the first and fifth ro,md. (See Plate).

• Reduced at the 20th shell and 99th round to 6 lbs, 12 ozs.

t The latter were as follows :-from the 82-pr. 4 shot and 1 blind shell; from the 7-in. howitzer 2 loaded shells; and from the 40-pr. 3 shot and 1 blind she11.

The extreme penetration of those missiles which struck within 9 feet of the central line ( and therefore almost directly upon the surface), may be thus defined:-

One 40-pr. shot penetrated 5 ft. 5 in. at course 90. One 82-pr, shot struck on course 50, on the 1!ew brickwork which closed the doorway.

This brickwork was laid in cement, and had been finished about six weeks. The shot penetrated the wall, which was 7 feet 6 inches thick, at the junction of the old and new surfaces, which were not bonded together, glancing a little downwards. It broke out about eight bricks on the inside, belonging to three courses1 and was lying on the floor. The hole externally was about 2 feet in diameter.

Another 82-pr. shot struck sound brickwork on course 92; passed through the wall 7 feet 6 inches thick, about 2 feet above the springing of the arch1 strnck the central pier, ancl lodged itself in the floor at the foot of the pier. The superficial effect did not extend so far as in other instances; the brickwork was broken over an area of 2 feet 9 inches by 2 feet 6 inches; the hole was clean.

A blind shell from a 40-pr. struck course 80, and penetrated 4 feet 2 inches, surface broken over an area of 1 foot 7 inches by 1 foot 6 inches.

A blind shell from an 82-JH. struck coul'se 28, and penetrated 4 feet 3 inches1 disturbing twelve courses, and breaking away the bricks over a surface of 2 feet 6 inches by 3 feet.

A 7-in. plugged shell struck course 601 and penetrated 4 feet 3 inches. A live shell from a 40-pr., (bursting charge 2½ lbs.), struck course 901 penetrated

before bursting about 5 feet, making a crater 12 feet wide at the surface, and diminishing to 2 feet at the depth of two or three bricks. Inside the tower the wall was considerably shaken, and seven courses of hricks were broken away.

A live shell from the 82-pr. (bursting charge 5½ lbs.), struck course 68 within the crater of another shell and penetrated about 4 feet.

A live shell from the 7-in. howitzer struck course 48 in sound brickwork, penetrated 4 feet 3 inches, producing superficial injury over 5 feet 9 inches in width and 9 feet

9 inches in height. The total quanlity of brickwork displaced up to this time was estimalcd at about O tons,

or 162 cubic feet.

4 ON TUE INCRE.-\Sl:;D POWER OF BREACHING WI'fll RHLEU ORON ANCE,

u After to.king Photograph No, 2, the firing was resumed with live shells; se,·en rounds were fired from each piece : one 6-iuch shell burst prematurely, ns did four others subsequently. .

" The Tower was not examinecl again until after the 2ith round, when 1t wns found that the surface was broken from the 70th course to the 110th course of bricks and over a width of 18 feet i at about the 72nd course, a large opening appea~·ed in the wall, immediately l~nder the spring of the arch, the ~rickwork of which was visible from the outside. The crater formed by the 1th round, near the doorway, had been much increased, and now extended from the 45th to the 80th comse o,·er a width of 8 feet. The 2ith rouncl (a 6-iuch shell) g razed the nearer side of the embrasure of the ~\•est window, and. buried it~elf in the opposite side, where it penetrated 1 foot 6 mches ; the explos10n, occurnng in an open window, did comparatively little clamage. The interior, however, was much dilapidated, and daylight was visible through three openings, viz., the one made by the 7th round, a. large hole between courses 70 and 80, and a smaller one rather higher up and to the left of it. The next 6 rounds, to the 33rd, were fired in two salvos, and had the effect of enlarging the three open­ings into a breach about 12 feet 6 inches wide, and 10 feet high externally. The central pillar w·as fully exposed. A quantity of debris had been carried in, sufficient to coYer about one-fourth of the interior ; there was a settlement of about 2 inches in the portion of the pampet immediately over it, and besides the two cracks between which this settlement was observable, there was a third crack Yisible about 3 feet to the left , and the brickwork had started outwards from the granite cmb or racer stones between 2 and 3 inches. It was observed, howeYer, that the roof was still undistm·bed, the asphalte not even being tracked.

• 1 Photograph No. 3 was taken at thfa stage. " The practice was reswned with the 40-pounder and 6-inch gun. Seven solid

shot and 2 shells were fired from the former, and 9 shells from the latter, 2 of which burst within 50 yards of the muzzle of the gun. The 38th shot struck the central pillar ancl carried nearly half of it away. The 41st shot brought down a large mass of the parapet, exposing the granite mu·bstones and racers. The practice of the fu-st day terminated at 7 p.m. at the 51st rouud, of which 4 i took effect.

u The appearance of the Tower at this stage is exhibited by Photograph No. 4, which was taken the following morning. The breach was 13¼ feet wide on the inside, and 24 feet wide on the outside i the interior was completely open from about ~6 feet aboYe the ground to tlie top, exposing the top of the central pillar, of which less than half remained, the circumference being reduced in one part from 14 feet to 8 feet 4 inches; about 4 feet of the still remaining wall was a mere shell, kept up by the rubbish and debris behind it. The unsound part of the wall extended about a foot and a half on either sicle, beyond the inner edge of the breach, which was well defined; beyond this distance the wall was almost uudishn·bcd. The opening in the parapet was 15 feet 8 inches wide, one granite ra,cer stone had fallen, two more were only held up by the iron racer, a fourth hu.U btarted 2 inches, the rest were unclistm·bed. A coping stone containing 7

ON ·rnE INCREASED POWER OF DREACIIINQ WITH RIFLED ORDNANCE. 5

cubic feet had been thrown about 20 feet f'rom its position. One SO-pounder shell had entered the doorway of the small stair which is made in the thickness of the sea-wall, about 18 inches below the coping of the parapet, and had ex~ ploded on its course through, knocking away the outside stone with a portion of the brickwork. The splinter marks inside the Tower were numerous, but not very deep; one 40-pounder was fow1d bmied in the brickwork, which the point had penetrated to a depth of 3 feet 2 inches: the other marks were little more than bruises, and did not weaken the wall to an appreciable extent.

"The practice was resumed under very unfc.wom·able circumstances of weather; the rain falling in torrents, with a strong south-west wind across the range.

" The firl)t 8 rounds carried the breach downwards, but it was not until the 72nd fl'om the commencement that the central pillar was completely knocked away, and so excellent was the quality of the bl'ickwork that it continued to sustain its own weight and that of the centre pivot-stones, "''l.th the 6-pounder iron gun which formed the pivot, until the 144th round.

H The 7-inch howitzer was fu·ed again alternately with the other two guns from the 69th to the 136th round.

" The state of the Tower at this stage is exhibited by Photographs, Nos. S, 6, 7, 8, and mav be described as follows:-

" The parapei was demolished for a distance of 63 feet, measured on the exterior circumference. From hence the opening contracted to an external width of about 35 feet at the top of the breach, which was 20 feet abo,,e the ground, with a tolerably good ramp. The opening was about 24 feet wide in the clear inside. Very little of the vaulting remained. The interior face and superior slope of the parapet on the sea front, w·hich was taken in reverse, -were greatly shattered, but no effect was visible on that side externally, except from the 6-inch shell ah-eady referred to, which penetrated the parapet. The few shells which struck the inner sw·face below had not broken the plaster outside. The effect visible on this sw·face was the formation of a regular exca,ation in the wall from one to two feet in dc1)th, where some flues had been formed in the imlicl, but with no rents or cracks around it. There were a.lso numerous super­ficial bruises from splinters of shells. It was observable, generally, that the brickwork showed very little tendency t-o crack, or start, or break away in large masses; some of those strewed over the breach, and derived principally from the vaulting, were, howe,er, large enough to have required breaking up before it could have been 11rudently stormed. The clebris extended about. 28 feet to the front; one piece of the stone coping, of about 1 cubic foot., was thrown, by the bursting of a shell, 35 yards from the Tower; another, of 2. cubic feet, 18 yards; fragments of brickwork were found as far as 150 yards from the Tower, and within 80 yards they were numerous. It was calculated that about 6,JOO cubic feet of brick and stonework were displaced by the fire, amounting to about 362 tons in weight. This was effected at the expense of 1,200 lbs. of 110wder in cartridges, and 650 lbs. in bursters for the shells. The weight of iron thrown was 10,850 lbs.

11 The precision with which the guns could be directed upon any point it was intended to strike gaYe them ad,;-antages with which no smooth-bored ordnance, firing from such a distance, could compete.

6 O:'.'f THE INCREASED POWER OF DREACIIINO WITII RIFLED ORDNANCE.

" One 40-pounder shell and fo•e 6-inch shells burst a little way in front of

the guns. . . , "The percussion fuzcs employed were too delicate for tlus sen1rc-. :Many

of them exploded with comparatively little effect in grazing or passing through the debris j few, if any, of them penetratecl the brickwork before ex11losion far enouo-h to exhibit their full power. This can easily bo remedied by a moclifi­catio~ of the f'uze, which is at present better adapted for u;:;e against ::.hips than ma:sonry. The quality of the brickwork aud mortar was first-rate j the resistance of the yaulting more particularly elicitccl much admiration. It held upi as already stated, long after the supporting pillar was knocked away, nnd only yielded to repeated direct blows, such as could not have been given at that clistance by any other than rifled guns."

Trials were subsequently made to breach a similar Tower, from smooth-bored 68 ancl 32-pounders, at the same range of 1,032 ya.rcls, and the result may be deemed altogether a failure, both accuracy of fire and Yelocity of the missiles being quite deficient for such a range.

At 500, or perhaps 600 yards, the supe1·iority of the rifled ordnance would probably have been very little, if any.

No comparison can be drawn, as has sometimes been attempted, between the abo,e stated effects 11roduced with the Armstrong gun of large calibre, and given quantities of ammunition, with what is recorded as the expenditure in forming breaches during sieges, been.use the latter were made with much lighter guns, which at long ranges will make a great difference ; and also includes in the expenditm·e the casualties, irregularities, and waste on actual service, which will create a great excess beyond what is used in deliberate experiments at home; and lastly the practice was against substantial masonry escarp walls, backecl wi.th solid earth, which is not to be compared to the destruction of a tower.

The results of recent experiments a.t Juliers with rifled cannon have confirmed the possibility of breaching Carnot walls, block-houses, &c., even where coverecl from view by i.ntenening works ; but this has been done many years ago at "' ool wich with the old ordnance; it can be effected however at greater ranges with the rifled, and with a greater im11etus given by each blow, than where the shot and shells, as with the old guns, were necessarily" lobbing" shot fired with very small charges.

This is a practice however that will be of very partial utility in real senice, inasmuch as it is blindly executed, without a sight of the object aimecl at, or the slightest knowledge of any errors in the firing. At \Voolwi.ch and Juliers, &c., the distance from the battery to the walli and the height and circumstances of the intervening mass, were known to a foot; and after every roundi obserrntions of errors in the firing could be, and probably were, made ancl notified to the battery. Nothing of the kind would be the case ata siege, and therefore it may be ~elcl that _such effects as were produced at those places, of' breaching walls belund covenng masses so near as they arc represented to have existed at those places, namely, within 60 feet, as at Woolwich, and 100 feet, as at Juliers, assuming that the cover itself was not susceptible of being reduced by the fire,

0)1 'l'llE INCRE,\SEO POWER OP IlREA.CIIING WlTII RIFLED ORDNANCE, 7

could not be obtained on actual service; at the same time, where there is a considerable distance between the wall and the cover before it, in the line of fire, such as of a caponniere at the end of the ditch of a work, much less refinement in the fire would be necessary, and the effect might be produced by a reasonable extra ex11enditure of ammunition; and here no doubt, in most cases, the rifled would have great advantages over the smooth-bored gun by its longer range, nnd firn at lower angles of ele,·ation.

These are circumstances that will therefore require to be attended to more than has hitherto been thought necessary in the designs for works of defence, where detached masoru·, constructions are connected with them.

There cannot be n clo~bt of the over-powering effect of the broadside of a man­of-war which can lay itse1f alongside of a low, closely concentrated battery on the shore ; the effect, however, is produced on the embrasures and parapets, or if the gw1s are iu casematcs, on the embrasures; in either case by a great mass of scattered fire directed generally towards the object; a real effective (still less a practicable) breach coulcl hardly be made by shipping in any good esca1·pwall backed by earth; nor e,en in a tower or block.house, under any opposing cannonade, eYen with rifled guns, for want of that absolute stability required to ensure the necessary precision of fire.

Though not coming absolutely under the definition of breaching, an important element in the reduction of works of defence, is the destruction of parapets, traverses, &c., which, being of earth wherever practicable, suffer greatly from shells, in proportion to the quantity of powder they contain to act as mines, and the precision with which they can be directed to the most advantageous depths within their surfaces ; and here the rifled ordnance possess very great adnntagcs.

J. F. B.

PAPER II.

ON A PROPOSED METHOD OF CONSTRUCTING FIRE-PROOF BRICK-ARCIIED

FLOORS, DEVOID OF ANY LATERAL THRUST, AND WITIIOUT TIIE USE

OF TIE-Roos, CAPABL:E OF CARRYING THE IlEAVIEST WEIGHTS, WITH

SUGGESTIONS FOR THE APPLICATION OF THE SAME SYSTEM TO THE

ROOFING OF MAGAZINES, IlOMB-PROOFS1 AND CASEMATED CONSTRUC~

'r!ONS GENERALLY.

BY CAPTAIN FRANCIS FOWKE, ROYAL ENGINEERS.

In the spring of 1858, at the solicitation of the ,var Department, I undertook to prepare a design for a proposed storehouse on the banks of the Thames at Rotherhithe, to contain the arms and camp and barrack equipage of the army.

As the building contemplated in my design was of considerable extent, and intended for the reception of a variety of articles, all of vital importance in a military point of view, and some of them of a more or less combustible nature; it wns necessary that such a building should be constructed in such a manner ns to be as safe as it could reasonably be made from the danger of any accident by fire. ·

Passing over the obvious preparations in the shape of water supply, fire­engines1 &c., the primary conditions necessary to effect this safety were, that the building should be constructed throughout of' materials difficult of combustion, and that its interior space should be so subdivided by masses of such material as to give the best chance of confining any accidental fire within the smallest possible limits.

To accomplish both these ends it was necessary to have, if possible, a thoroughly efficient system of fire-proof floors throughout the building, and also that these floors should be supported as far as possible upon pillars or supports of incombustible material.

It was thus necessary to a,oid the use of iron columns in all situations where they were likely to be surrounded with combustible articles of store-and where~ ever iron was indispensable, to case or envelope it within a heat-resisting medium, such as brick or fire-clay.

It became at once apparent that these conditions entirely forbade the employ• ment of the ordinary flooring of parallel girders of either wrought or cast iron, carrying brick barrel vaults cmd connected with iron tie-rods to sustain the thrust of those vaults ; as in case of fire the wrought iron ties would become so lengthened and weakened by the heat that the failure of the vaults would be nn almost certain result. The matter would not have been much mended by running these vaults transversely in a long building, so that their combined thrusts might be received by buttresses or other arrangements at the ends, for in that case the failure of any one vault would have been 1·uin to the whole.

The floor known as Fox and Barrett's, and constructed of wrought iron I shaped joi.Ets filled in between with concrete, was thought to be ina.dmiHible, as from tho

PROPOSED METHOD OF CONSTRUCTING FIRE-PROOF BRICX'.-ARCHlm FLOORS, 9

spn_n befng too great for a single floor, a large surface of the lower part of the mam girders would be exposed to the action of heat; besides which it was !>robable that the heat generated ftom the burning of large quantities of' rnflammable stores would be sufficiently intense to destroy the concrete, upon the integrity of which this description of floor entirely depends.

The problem to be solved was in fact to construct a floor that, with the least possible thickness, should be capable of sustaining the greatest weight; that it should be free from nll tie-rods, and that each bay or division in which it might be constructed ~hould be so neutral (if I may use the term) as regards lateral thrust, and so independent of thnse surrounding it, that the failure of any number of bays would have absolutely no effect upon those in their immediate ,·icinity.

It so happened that both the length and breadth in feet of the building designed by me were nearly multiples of 16, and as 16 is a convenient length for iron girders, it was decided to divide the floors into squares of which 16 feet should be a side; and that these squares should be carried on brick or stone piers at their angles.

As all these squares were precisely alike, an account of the method in which it was proposed to floor one square will be a description of the entire floor; and as an experiment was immediately ordered to be made upon the peculiar method of flooring then proposed, it will suffice, in describing the method, to give a detailed account of the experiment actually made, with its results.

The portion of floor constructed for experiment is composed of four cast iron girders, in section thus shaped A, (the flanges being downwards), bolted together with four ¾-in. bolts at each end, the ends of one pair of girders being shaped to fit against the sides of the other pair, to which they were bolted. (See Plate.)

The depth of the girders in the middle is 1 foot 6 inches over all, and at the C'nds 1 foot 1 inch, the lower flange's being horizontal and the upper edge curved parabolically. (See Figs. 5 & G.)

These girders rest upon four brick piers, 2 feet square, ha,·ing upon them stono blocks 1 foot 11 inches square and 3 inches thick: these blocks are 13 feet apart between faces, giving the girders a clear distance between supports of 13 feet. The stone is 11revented from being in contact with the iron by a felt packing.

lletween the girders the space is arched over by a 9-in. groined arch, com­posed of two courses of bricks laid on edge, stretching parallel to the girder from which the arch they compose springs; these bricks are set in Portland cement ancl are cut to mitre at the line of groin; the versed sine of the arch is 9 inches, or less than T1'ith of the span, the clear distance between bearings being 13 feet 11 inches, ,,iz., between the opposite flanges of the girders.

The spandrels, or spaces over the haunches, were filled in with concrete to t.he level of the crown of the arch, forming an even surface all over.

WEIGHT AND METHOD OF LOADING.

The load was laid on a surface of 6-i square feet, or 8 feet by 8 feet, in the middle of the floor.

The first course laid on wns composed of Fox and Barrett's wrought iron I shaped joists, which happened to be on the spot nt the time: these joists were laid sideways and placed close together 8 feet wide and 8 feet long ; across these similar joists 20 feet long were laid to a width of 8 feet, ancl ,w T' ,nd

10 PROPOSED METHOD OF CONSTRUCTING FIRE-PROOF BRICK-ARCHED FLOORS.

across these, other courses until a weight of 40 tons was obtained, no cffert being produced on the arch, beyond the bedding of the flanges of the joist• in the concrete.

'l'his weight of 40 tons was allowed to l'emain on for a week, no further effect being ,isible.

A weight of 12 tons was then added, more joists and bricks being placed on it: this gave a total load of .52 tons, or 16 cwt. and one quarter, per superficfal foot, on the loaded surface, and this caused a bulging out of the two opposite girders, to the extent of fths of an inch in each gil'der in the centre; but O!I

i-emoving the load, which was done after a further period of 48 hours had elapsed, the girders became perfectly straight, and no visible depression appeared in the crown of the arch.

The experimental floor having been constructed within a few feet of a slight iron building, it was thought unadvisable to continue the experiment up to the actual breaking point; from its appearance, when loaded up to the above-named weight, it would probably have stood a very much greater load, and at the height to which the load (of bricks) would haV"e reached, their fall would have been attended with considerable risk to the adjoining building.

The portion of floor to which this severe test was applied was in the most unfavourable position possible for bearing the great strain it successfully sup-1>orted-that is, it was perfectly isolated, and absolutely unassisted by any such Latcml support as would, under all ordinary circumstances, be afforded by the i,;urrounding squares.

Thus we have a floor supported only at four points, and having a bearing between those points of lJ feet from centre to centre.

The extreme thickness of the floor is 18 inches, and its mean thickness onh· 12 inches. It has borne a weight of 16} cwt. to the superficial foot over its weakest part, and under the most trying circumstances. It is independent of extraneous lateral support in all directions, and it is also free from the defect above-mentioned of depending upon a dangernus system of wrought iron ties.

It is thrown out as a suggestion whether this floor might not be usefully employed, not only for the purposes for which it was originally designed, but also in casemates and in bomb-proof buildings, such as large magazines wliere, ::tCco1·ding to the present system of construction, there is so great a sacrifice of valuable space in the massive haunches of the arches and groine-.

In the case of magazines it would probably be necessary to case the exposed flange of the girder ; but this could be done with tiles made for the purpose a.ncl hung on the flange itself (see Fig 4).

In carrying out any work on this principle it would not be necessary to use the A girders; the common J. girder can be used with either Portland stone skew backs or bricks moulded into the same form. The expense of bolting the girders at the angles might also be a·rnided by simply cast.in..,. the bottom flan,,.es with lugs and corresponding. recesses a_lternatcly, when the 0girdcrs would k;ep themselves connected by then· own weight and that of their load. In a work of any magnitude _the use _of moulded_ bricks would Sll}Jersede the necessity and expense of cuttmg to mttl'e the gt·om5.

F.F., 2it-h April, 1860.

I l >-1 -,--,-----.,.-------=!• i ..

'

E]PYa1ion ol' C-Ol.lner1iott of GirclC'.l·s.

11

PAPER III.

Ox THE Fon:u OF TUE YouSSOIRS OF A CONVERGENT Ancrr OR YAULT.

BY 'l'IIE REV. JOHN F. '!'WISDEN, M.A.,

PROFESSOR OF 1\1ATIIEMATICS IN THE STAFF COLLEGE,

(Communicated by Lieut. Home, R.E.)

(1.) It is occasionally necessary to construct a casemate with conYergcnt walls, for instance when the case mate is situated at the salient angle of a bastion ; • when this ocmus the interior surface of the ,ault ceases to be a JlOrtion of a cylinder, and the rules for cu,tting the ,,oussoll's of an ordinary c-ircu1ar arch are no longer apJJlicable. The object of the folloWUlg paper is t·o investigate certain geometrical propositions connected with the form of the Yau.It referred to, and to deduce from them a series of practical rules by which models may be macle of any given voussoirs. The writer is not aware that the question has e,·er before been in,,estigated, and he trusts that the rules he has dt·a,•n1 up may be of some practical value.

(2.) The form of the vault can be thus defined :-There is a semi-circle placc-d with its plane vertical, there is a ,·ertical line so placed that the plane which contains the line and the centre of the semi-circle is at right angles to the plane of the semi-circle; a horizontal line which moYes in such a manner as always to pass through both the straight line and the circumference of the semi-circle will trace out the vault in question. It is obvious that a person who stands inside :--uch a vault will see that the longitudinal joints are horizontal lines, but that they differ from the corresponding joints of a common circular vault in this, that instead of being parallel they converge to a vertical line. Such a vault may he called a convergent vault. It may be added that if the horizontal joints above-mentioned are projected on a horizontal plane, the projections will converge to a point, and in this respect differ from the joints of a semi-circular vault which project on a horizontal plane into parallel lines; the projections on a vertical plane at right angles to the plane of the circle will be the same in both cases. ,.

(3.) To determine the equation to the sul'face of-1he.°'i,onYergent Yault. Let BDC (Fig. 1) be the circular section, the centre of wln~h is A: draw AO at rig·ht auglcs to BDC, and let OE be the line of conYergcncc; take P any }Joint in DB, and draw the horizontal line PP' passing through OE, the requirerl t-iw:face is the locus of the line PP'; draw PN at right angles to AB, join NO,

• In some works this has been done by building a square casemate; which involves a loss of space at a very \'ital part of the work.

•

12 ON TIIE FORM OF TIIE YOUSSOIRS OF .-\. CONVERGENT ARCII OR Y.-\.ULT.

take p any point in PP', draw pn nt right angles to NO, and na at right angle~ to OA i denote Oa, an, np by .2,, y, z respccthcly, whieh assumes OE to bo thc axis of :::, OA of x, and a line d.i·awn to tho left through O at right angles to hoth to be the axis of Yi also let OA, AP, ancl PAB be denoted by a, 1·, and </> respectively. Then we have

1m = PN or z = 1· sin rp Also NA:AO::,ia:aO

or

The required equation.

rcoscp:a:: y: x ay

.·• ;-=rcos<p

z2 + a2ya = r'l x'

(4.) To determine the equation to the section of the convergent vault made hy :.my nrtical plane 1mrallel to the cll'cular section.

Let x ha,c any particular value x 1 , then y and: are the co-ordinates of any 11oint of this section, and therefore its equation is

z'2 + y2 1. ;:; r2 X1'2 =

a'

Suppose (Fig. 2.) the plane of the paper to be the horizontal 1ilane through O; take BA= AC= r; OA at right angles to BC equal to a, Oa = x 1 and draw bac at right angles to AO ; then

01'

ba : aO : : BA : AO

ba = rx 1

a

Hence the required section is an ellipse of which the principal semi•axes arc r. ancl ba: if a is between A ancl O the vertical axis (r) is the major axis, and tht> horizontal axis 0a) :is the minor axis; on the other hand if a :is beyond A, the ,·crtical axis (r ):is the minor axis, and the horizontal axis (baJ is the major axis.

( 5.) To obtain a 1,ractical rule for drawing the elevation of any vertical secti011 of the vault macle by a plane parallel to the circular section.

Draw (Fig. 3) BACO as in Fig. 2, and let it be req1.1ired to draw the elevation of the section '"hlch is situated nt a distance Oa from O; take ad equal to AB ancl draw the ellipse bd.• Next to draw the edges of the voussoirs; let llQ bc­onc of the edges of a voussoir in the cll'cular section; d.i·aw PN at right angle~ to BA, join NO, cutting ab inn: d.i·a";, np at right angles to ab cutting the elliptic arch in p ,· then p is the point corresponding to P: finally at p draw pq a normal to the curve at p; this will be the edge of the voussoir in the elliptic· section corresponding to the edge PQ in the circular section. Of course thC' normal in the case indicated can be d.i·awn as follows: with centre b and racl:iu~

• It is plain from this that to form the centering of the vault a sufficient number of the curves should be drawn by the above rule; if these are constructed on wood and placed at the proper distance apart the required centering is at once obtained,

ON THE FORM OP TRE YOUSSOIRS OF A CONVEROENT ARCII OR YAULT. ]3

arl dC'scribc a circle cutting AO ins and s', these are the foci of the ellipse; join sp, s'p, and bisect the angle sps' by the line qp, this line is the required normal.

(6). Practical rule for forming the model of the front and back faces of any YOUSSoir. •

The rule in the last article will enable us to cletermi.ne the form of the ft·oht and back ends of any voussoirs i let them be EFOH, KLMN, in Fig. 4, and i-uppose them to be cut out iu Jllanking ; it remains to fasten them together in the proper relative 11osition; the rule for this is sotncwhat difficult to enunciate, but the thing itself is not hard to do. Draw (Fig. 6) ABD, AO, BO, as hcforc; let QPP 1 Q1 be the circular face of the voussoir corresponding to EFGH and KLMN; draw PN, P,N, at right angles to AB, join ON, ON,; let Aa, Aa 1 , be the distances of the faces of the required YOussoll' from the circular section; ili·awab, a 1b1 cutting ON, ON1 inn, m, and np m 1 respectively; produce ba, b1a 1 , and nail together three pieces of plank so as to form a tl'iangular prism whose plan is rstu, and eleYa6on RST,-it should howeYcr be made shorter than aa 1 by twice the thickness of the plank from which EFGH and KLMN have been cut; if these are nailed on to the ends of this prism thev will be at the right distance apart. Nail EFGH on to one end, it onh· 1·cmain's to nail KL~IN on to the other end in the right relative position; 01~e way of doing this is shown in Fig. 6: draw on a horizontal table the lines au, a 1 m, mn, n 1m, aa 1 the same as in Fig. 5. Place EFGH in such a manner that the point F is at n, and G vertically over n1 ; if its plane is kept Yertical by belllg; sup110rted against a vertical board YZ, whose horizontal edge X Y coincidc8 with an, the prism USTR will be in a position fitted to receiYe the piece KLMN1

which must be placed against it as indicated, the point L coincicling with m, and l\[ ,·ertically oYer mu• and if when in this position it is nailed to the end of the prism, the model is completed so far as the form and position of the two ends are concerned; it remains now to form the model of the sides of the ,,oussoirs.

(7.) To determine the equation to the surface of contact of two continuous voussoirs.

Produce (Fig. 3) qp to cut be or be produced in G; suppose the ellipse to he hm1ed upward round be through an angle of 90°, it is eYident that the surface in que~tion will be the locus of the line qG ; hence take H any point in it, draw UK at right angles to be, denote Oa, aK, KH by x, y, and z respectively; we are to find the relation between x, y, and;;, Now in the ellipse

but

and

aG : an : : ad1. - ab<J : ab 2

xr cos if> an= --­

a

ab=~ a

• It may be of use to remember that the height of l\f and G above m1 and n 1 is the i.ame as the vertical heightofP 1 above P. It ,vould also (probably) be found convenient to steadg the two ends between two vertical boards: it might even be found convenient to fasten the ends temporarily to two such boards and then to introduce the prism between them i but this can be safely left to the workman,

11 0\ THE roR\l OF THE YOUS~OIRS OF A CONYERGENT .\Il('ll on. Y \lt,T.

dH':Tf11·c aG = ar cos</> X aJ .- x, a x'

,1g u.i 11 Jm : "G : : HK : KG

. rx cos </) xr cos if, a1 -x11 xr cos <P a1 .,. , c,1· r :--in rp . __ a_ + --a- X ----;;- : : : : y + -a-- X -.,-.-

or I' hlil </> : ar cos <p : : z : '!I + r cos q:, • a2 - x 2

•

X a X

thcrcfol'c z = xy tan <f, + a~~~ 1· sin <p,. a a

. (!)

is the required equation.

(8.) Now in order to make n. model of the surface of contact of two conti­~uous voussoirs, we have to ma.kc a model of that portion of the bUrface (who~;e c·quation is (1) ) above the horizontal line drawn through Pp. But if we ob1nin the cw·vc of intersection of this surface with any plane and place it in a proper vo:sition relatively to the line Pp, and then draw from each point of it a line nt right angles to Pp this will give the surface required; the best plane of inkr­:-cction sccnL'i to be one passing through Q (Fig. 3) at right angles to QP.

It is evident that this plane is at right angles to the plane vz; conscq_ucntl~· its equation will be identical in form with that of a line at right angles to AQ, or if AQ = tJ, it will be

ycosq:,+:su1if,=r' ... . .. (2).

(9.) To determine the equation to the line of intersection of the }Jlanc (2) with the surface (1) referred to axes in the cutting plane.

Since the eq11ation to the sm.face is

: = xy tan q, + a' - x' r sin </J a a'

b,r eliminating z we obtain the equation

xy tan </) sin q:, a 1 - x~ r' = a + -a-,- r sin' if,+ y cos q,. . . (3).

'l.'his is the equation to the projection of the line of intersection on the plane of xy. Let (Fig. 7) Ox, Oy, 0::::, be the axes of x,y,:., and x'y the cuttin,.,. plane, let it cut zx in O'x', and ZJI in O'y; and take these lines as the axe: of co­ordinates in the plane; let P' be a point iu the curve of intersection, di·aw P'N' at right angles to O'x:; then _if -w-e call O'N', N'P', x' and y' respecth·cly wr have to find the equation which connects x' and y'; draw P'P at right angles to the plane xy, and PN at right angles to Ox then ON and NP arc the :i: and!/ of equation (3). But the angle y O'O equals if,, hence we have

:z = :,;' y=y'sinq,

ON TUE }'ORM OF TUE YOUSSOIRS OF A CONVERGENT .\RCU OR Y.\ ULT. 15

:rnU the rcqui.red equation is

, x'g' tan <jJ i:.in'l <jJ a'l - r''l . . ,. = ---a--- + -a-.- r srn'<p + y' is11l </> cos <t,

ot· suppl'essing the accents for the sake of convenience

,., ,·sin• q,-xyaton <f, sin• <f,-ya• sin<t,cos<f, + a• (,·'-r sin• <f,) = 0 . (1).

This equation is eYidently that to a hyberbola; it may be written in the f'urm

Ax• - Bxy - Cy + D = 0 . (,)) .

,\-hl•l'C A = r si.11 2 <jJ, B = a tan <jJ sin' </), C = a' sin q, cos </), ancl ]) = a"

(r' -- r sin' rt,). It remairns to discuss this equation.

(10.) To find the as)mptotes to equation (5).

"·rite it in the form

Ax•+ D Y= Bx+c

Thcn it is plain that the equation to one asymptote is

.\bo tlw al10Yc equation cnn be written

Ax + !!_ X

1r=---B(1 + ~)

Ax =B

Bx

AC D B'- + llx +

Tht·rcfurc the.: cqml.tion to tl1e oth~r asymptote is

Ax AC y = --B- - E>'

The co-orUinakR of the point of inter!ection of the asymptok•s i.e. of tlll' c:cntre

of the c1.U'H', arc C 2A('

x=- Bnndy=-~-··

aml if O is the acute angle between the asymptote.!:I

A Cotan 0 = B.

or A sin. 0 - B cos 0 = O.

16 ON THE FORM OF THE YOUSSOIRS OF A CONYEROENT ARCll OR VAULT.

(11.) To determine the equation to the curve (5) when the asymptotes are axes.

( a,) Transfer the origin of co~ordinntes to the centre ie. for x and y write

C y - 2AC, then we obtain ."!' - if ancl ni

\ ( x - i )' - B ( x - i) (y - 2:.c ) - C (y - 2~~C) + ]) = 0.

0 1' AC•+ B• D

Ax• - B.,y + B• = 0.

( b.) Tnmsform the axes to the asymptotes.

LL•t 1-1.t:, Hy (Fig. 8) be the rectangular a.xes tlu·ough the centre of the cmTe alter the transformation in the last section, these are parallel to the original axt't:i ; draw a'H in such a manner that ,r'Hy = 0; take P any point of the cnrn.• and draw PN'N parallel to Hy, then PN', N'H, m·e the new co-ordinates of I', mul PN, NH are the old co-ordinates; or the transformation will be effected bv ~nhstituting in the equation of the last section x cos 0 for x, and y + ,T sin 0 ii,r y. "'hen this is done the required equation can be written

AC' +B'D .,., sin 0 ( A sin 0 - B cos 0) - B.,y sin 0 + B' = O.

JJ11t by Art. (10)

Thf'refore

Asin0-Bcos0=0

sin'l0= -~ A• + B•

rirnl t hnefore the equation required is

,,y = (AC• + B'D) v'~ B•

(12.) Hence substituting for A,B,C,D we obtain ( ,. J For the asymptotes referred to the original co-01·dinates

11.)

(~-)

a:=- acotan'l q:,

y= r cotan </> tc - r cotan s <p a

r1,.) Fo1· the Clll'Ye referred to the asymptotes, we obtain after reduction

·'"!/ = cosec• </> cotan <f> ( r' - r + r cotan• </J J y'r' cotan• </>+a' (l:J.) To draw on the cutting plane the projection of the horizontal edge

tl1ru•1~h Pp (Fig. 3). Ll't (Fig. 9) ABD be the circular section, PP1 the horizontal line whose pro­

jection on the cutting plane it is required to find, produce AP to meet the cuttino­plaue in Q; this will be one point in the projection and its position is fixed b;

0~ THE FUH.M OF 'fllt vorssoms OF .\. COXYEJlGENT AilC'Il or~ VAULT. 17

the fact that on equals a, and nQ equals 1·' cotan <p. Draw l)'Q' at l'ight ann•k ~ to O!J, then Q' is another point in the projection and it is evident that ~Q' equals OP' cos q, which equals(•' cosec q, - ,. sin q,) cos q, ==

r' cotan q, - r sin q, cos q,.

This gives the position of Q' on the plane, and therefore the position of the required projection is known. The method of using the equatiorns now obtained will be bei::it understood by discussing a particular case.

(14-.) Given n. cascmate 20 feet wide, radius of front arch 20 feet (so that the arch is an arc of 120° and the smallest "alue of q:, is 300) the depth of the case~ mate 30 feet, the distance of the line of convergence from the circular section 50 feet. It is required to ch-aw the Clll'Ye and the projection of the horizontal line (of Articles 12 and 13) when</>= 45°, the height of a circular voussoir being 2 feet (Fig. 10).

Here we have a = JO, r = 20, r' = 22, <p = 4J0 •

Hence the equations to the asymptotes are

2.i· a: = - 60 and y = 5 - 20.

Take Ox, Oy at right angles, measw·e Oh = 50, draw Id parcllel to Oy thit1 line is the one asymptote; take Ok = 20 this will be one point in the other asymptote and On = 50 this will be another point in it ; join nk and produce it to meet hl in l, nl is the second asymptote, and t is the centre of the curve.

Next to draw the curve, its equation becomes on substitution

xy = 2369·5.

, From this we can determine as many points as we like; in the diagram the following have been taken :

X = 48•86, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150,

and the corresponding Yalues of y are found to be

48·86, 4i·4, 39·5, 33·9, 29·6, 26·3, 23·7, 21-6, 19·7, 18·2, li, 15·8,

the cUI·ve is then drawn as indicated.

Finally, to draw the projection of Pp, we have :-On = .50, and nQ = 1·' cos <p = 22, which gives the point Q of the projection, situat~d in the curve as

it plainly ought to be; and next OQ' = 22 - 10 = 12, gives the second point of the line.

If we take nin = 30 the depth of the vault, and draw pgm parallel to Qn, tho portions of the curve and line required arc Qp, and Qq. A similar construction must be made corresponcling to every joint of the circular arch.

(15.) :Mctho(l of constructing a model of the surface of contact of any two contiguous rows of voussoiri::i.

Take two 11lanks (Fig. 11) and make the edge of one of them, AB, perfectly straight, anll draw on that plank the cw·ve BD which is the same as tl1e cw·ve

C

18 ON THE FORM OF TIIE VOUSSOIRS OF A CONVERGENT ARCil OR V.\ULT.

Qp in Fig. l O, making also tho angle at A the same as the angle Qqp ,· take an rxactly .similar piece of phtnk A'C' and draw the same Clll'Ye D'B' upon it, and then cut away the pa.rt indicated, leaving the curve D'B' as the edge. Now place the latter over the former at the requisite distance r1 - r, which in the present case is two feet, as shown in Fig. 12i the edge D'B' being plnced so as to be exactly vertically over the curve DB. Fasten a number of thin straight pieces of wood to these two edges, as shown by pq, p'q' p 11 q1' .••• ancl they will give the exact surface if sufficiently narrow and sufficiently close together; the <'xact position of any one (pq) is indicated by the lines pn, nq, where 1m is at 1·ight angles to the board ABO, and makes with AB an angle A.

( 16.) Hence we can complete the model of the voussoir described in Article 6. Suppose Qp (Fig. 10) to be the curve corresponding to edge P 1 Q1 of Fig. 5.

'Tnke na and na 1 in Fig. 10 equal to Aa, and Aa 1 in Fig. 5; draw asr, a 1s 11·u

parallel to nQ; cut out in plank the curve rr 1 and the straight line ss 1 , and fasten them together in the proper relath-e positions, as described in the last article. '!'hen, having made allowance for the thickness of the plankingi place this between KLMN and FGH (Fig. 6) in such a manner that sands, come to G and M, and rand r 1 to H and N; if thin and straight pieces of wood are then nailed on to,.,. 1 and ss 1 as before described, that face of the model will be com­pleted. The other face is made in exactly the same manner, except that the concave curve must be used instead of the convex.

N0TE.-The investigation is now complete; but one or two subsidiary points remain to be noticed. It will evidently be a great simplification if we can treat the curved line rr 1 as a straight line (Fig. 10). The object of the following articles is to ascertain when this can be done; we shall effect this by discussing more particularly the relation between the line Qq and the curve Qp ,· it must be remembered that though reference is still made to Fig. 10, the reasoning supposes that the angle <p has any value, and is not limited to the particular ynluc <p = 45°.

(17.) To determine the equation to the tangent to the curve, and to determine the point (T) in which the tangent drawn to Q cuts Oy.

Taking the equation to the curve referred to1 Ox, Oy, we have (Eq. 4)

F(.,y) = ,i•'r sin' <t, - xy a tau q, sin' q, - ya'. sin q, cosq, + a• (r'-r sin'q,) = 0

, ·. Differentiating,

F'(.v) = 2xr sin• <t, - ya tan q, sin' <t,

F'(y) = - xa tan q, sin' rt, - a• sin q, cos q,. anll therefore the equation to the tangent at any point (xy) of the curve is

(y' - y) (xa tan <j, sin q, + a' cos </>) = (,r'-x) (2xr sin q, - ya tan q, sin q,) Now the co•ordinates of Qare (Art.13) x = a, and y = r' cotan <p. ,Vhcm:o

the equation to the tangent to the curve at the point Q is, after reduction,

(y' - r' cotan q,) a = (>' - a) (2,· - r') sin q, co, q,.

Now OT is the value of y' derived from this cquatbn by writing,,,, = o.

ON THE FOR)( OF TIIE YOUSSOIRS OF A CONVERGENT ARCII OR VAULT, 19

. · , OT = r' cotan q, - (21· - r') sin q, cos q,.

Cor. But OQ' = r' cotan q, - r sin q, cos q, (Art. 13),

Hence subtracting Q'T = (r' - ,·) sin q, cos q, = 1 (r' - r) sin 2 q,

a ,·cry important conclmdon follows from this: Q'T equals zero when <p == 0, and also when <p = 90°1 in both cases QQ' coinciding with the tangent to the curve at Q, or rather with the cur,e itself, which for those values of <p dcgcncrate>J into a straight line. Next Q1T is greatest when <p = 45°, and is then equal to ¼ (r' - r) which is in all cases -very small. Hence the line Q•Q, though ,cry nearly coinciding with the tangent, will always cut the CUI'YC in Q, and therefore in some other point.

(18.) To determine the points of intersection of the line QQ' and the cune. From Art. 13. It is evident that the equation to QQ' is

r sin q, cos q, y - (r' cotan q, - r sin q, cos q,) = a x

If we substitute the -colue of y in the equation to the cm~•c the roots of the resulting equation will give the values of o: conesponding to the points of intersection; this equation is

.v' r sin' q, - x• r sin• q, - ax tan q, sin' q, (r' cotan q, - r sin q, cos q,)

- xar sin' q, cos' q, - a' sin q, cos q, (•·' cotan q, - r sin q, cos q,)

+ a' (r' - r sin' q,) = 0

which on simplification becomes

x• r cos• q, - ax (r' + r cos' q, - r sin• q,) + a' (r' - r sin• <f) = 0,

or xr cos' q, (x - a) - ar' (x - a)+ ar sin' q, (x - a) = 0.

whence the values of x corresponding to the points of intersection are

.:t1 = a

and a (r' - r sin' q,)

x'J. = 1· cos'l </J

{ ,., r'-r } = a - + -- tan' q, r ,.

consequently a•'l is always greater than .v 1 ~r the second point of i~tersect!on is always beyond the circular arch; and the d1Btance between the pomts of rntcr­scction equals

a (r' - r) sec' q, r

20 ON THE FOR'.\! OF TilE YOUS~OTRS OF A CONYF.RGENT ARf'TI OR V.H'LT.

(19.) Rule for the position of tho circular arch. If the height of the front arch of the casemate equals half its width, the

circular arch must be in front and no alternative is left; but if the height is less than half the width, the circular section may occupy any position beyond that section, in which the width of the casemate is diminished to the double of the height of curve;• for of course there is no reason why the circular section should be a semi-circle, and consequently the only limit on the position of the circular section is that it cannot be on this side of that section for which the width is twice the height of the curve. It would seem that the best position for the circular section is that in which the section is a semi-circle-i. e. in which the circular section is as near as possible to the line of convergence; for it is obviously desirable that the voussoirs should be as little skew as possible; in other words, that the curve Qp should as nearly coincide with Q q as possible. Now on this side of the circular section, the tangent to the curve at Q is between the curve and Q q, but beyond the circular section the curve is at first between Q q and the tangent-i. e. up to the second point of intersection-and afterwards Q q is between the curve and the tangent, consequently the curve and the line Q q are much nearer coincidence beyond the circular section than on this side of it.

It might be thought, at first sight, that there would be objection to using an arch in which <p may be very small, since then the right-hand side of Equa­tion (b ), in Article 12, becomes very large, and it might be feared that the curvature of the hyperbola would become considerable ; but then it will be observed (see Art. 12) that the point of intersection of the asymptotes, i'. e. the centre of the curve, goes off to a great distance, and consequently the part of the curve required will be very remote from the centre, i. e. it will very nearly coincide with a straight line. On other grounds it is obvious that when <p = O, and rp = 90°, the curve must degenerate into a straight line.

(20.) To determine the greatest distance between the curve and a chord drawn through any two points of it.

Let Ox, Oy be the asymptotes of the curve whose eqnution (Art. 12 b.) we will write fop shortness. (See Fig. 13.) xy == m.

Let P 1 , Pi, be t.wo points whose co-ordinn.tcs are (xu y'!.,) (x 2 , y 2 ) the <'quations to the chord drnwn through them is

or

• Geometrically thi s is not a limit; the limitation simply results from the fact that an arch of m<irc tli:111 18uu \\•m id br inadmissible. It may be remarked that the term •· be~·uud section" rnea1 1c farth er from the line of convergence than that section; while the kun •· on th is sitk of a g i\" en ~cctiv11 " means nearer to the line of convergence.

ON TUE FORM OF TIIE YOl'SSOIRS OP A CONVERGENT ARCH OR VAULT. 21

Since (r,, y 1 ) (T 2 , y 2 ) arc points on the cmTc. Now lcty· correspond on the cun:e to the ab~cissn .c.

Therefore "' JI'=-

and therefore y - y' = '!: _ _ __'!:__ (x _ :r ) = m (x, - x) (r - x, ) X1 X X1 xll l X X1 x'J

x being intermediate to x1 and x 2 • In the figm·e pp, represents y - y'; it is plain that y - y' will be max.imwn when

or when

,n Therefore the greatest value of y-y' is ;.;--;,; (v'x," _ ✓x,)'

Now suppose x, and x, to correspond to the extremities of any Youssoir, then if this value is less than a fraction of an inch, the upper edge of the voussoir may be treated as a straight line, and this circumstance will greatly facilitate the cutting of the voussoir, as well as the construction of the model. For instance, if, in Fig. 10 (Art. 14), we suppose a single voussoir to occupy the whole space between the dotted lines 60 and 90-and therefore to be nearly 10 feet

long-the greatest value of y-y' will be 2369 X ( y'9U - vsil)• which is equal 60 X 90

to 1 ·16 inches; the curvature in such a case could not perhaps be neglected. If we took the part of the curve that lies beyond the circular section, and between the ordinates 130 and 140, we should find that the greatest value of y - y' is 0·3 of an inch. It is evident from this that the curvature of the upper edges of the voussoirs will never be very large, and in most cases can be neglected; and con~ sequently that the main use of the curve drawn in Figure I O will be to fix the relative positions of the upper and lower edges of the voussoir. It may perhaps be added that the curvature of a voussoir when near the line of convergence may be considerable, it will therefore be unsafe to treat any portion of the curve (such as that represented in Fig. 10) as a straight line without trial, but if we suppose all the voussoirs to be of equal length, and if we find that the curvature of one of them can be neglected, then, ci fortiori1 the curvature can be neglected of all those which are more remote than it from the line of convergence.

It is manifestly quite essential that the curves (like that in Fig. 10) corres4

ponding to each joint of the ma~onry, should be drawn on a conside1·able scale and with gl'eat accuracy.

APPENDIX.

The fo1lowing article is a generalization of what has gone before, so far as the pun,ly geometrical portion is concerned: us at least one application may ea::;ily he -.uggcstcd by practice, it has been thought well to make the present addition.

(I.) The annexed figure 14 corresponds to fig. 3, and therefore need not bl"-' p~rticularly described.

L<t Q.\ = a, AN = !,, NP = k, and let the equation to the curve BD be

f(l,,k) = 0 ............... (!)

Lrt Om =.,v, tnn = y, tip = z, then

and

Therefore

z = k,

!I ,. -== -; ,i· a

i~ the equation to the convergent vault in its most general form. If we suppose ('m to have any particular value b, the equation (2) is that to a parallel scctifln. Hence the equation to the curve bd is

( ay) J z, 1' = o .................. (3)

It is evident that (I) and (3) arc curves of the same order. Xcx~, to determine the equat~on to the surface of contact of two contiguous

,ou~son·s. Draw the normal pq to the curve ad at p; this is the line which traces out

the surface in question. Draw PQ a normal to the curve BD at P, and let the angle PGB = <pJ then we have

f'(k) -f(li) tang,= 0

by thr- properties of the normal; also the equation to pq is

z'-z = - ;~ (y'-y);

, a ,(ay) dy f(z) +-i;-•f b. dz = 0.

ON THE FORM OF THE VOUSSOIRS OF A CONVERGENT ARCII on Y.\. UL'l' . :23

'l'herefore the equation to the normal is

b f'(z) z'-z = -. -(-) (y'-y) .

a f' ay b

Now, f'(z) =f'(I,) and f'( a:) = f'(h). Therefore the equation becomes

b ( M) z'-k=,; tanq, y'--;;.

Hence, suppressing the accents, and writing x for b, the required equation is

k xy tanq, x•h z- ·==--a- - -;;-tang:,.

which can be easily shown to be the equation to the hyperbolic paraboloid. ,ve thus obtain the remarkable theorem that "if a convergent vault is cut by "vlanes parallel to its front , and normals are drawn to those voints of the resulting "curves whicli a,·e i·n the same generatin,q line, the locus of the normals will be a " Hyberbolic Paraboloid whatever be the form of the front of the vault."

If we suppose the point O to be removed to an infinite distance, we have the

limit of ~ equal to unity, and consequently the equation to the surface

degenerates into z-k = tanq,(y-k).

The equation to a plane passing through PG at right angles to the front of the vault; which, since the vault in this case becomes a cylinder, is obviously the result that should be obtained.

(2.) The practical case alluded to at the beginning of the appendix is the following:-

Suppose the line of convergence not to be opposite to the centre of the fron t of the vault: Eg. Suppose the circular section to be BD B' and the point O of con,ergence to be opposite to the point A, which is not the centre of the circle. In this case if G is the centre of the circle, and AO = c, we have for the equa4

tion to the circle y' + (x - c)' = r',

and for the equation to the vault

( at/ )' z'l + ~- c == r •,

and for the equation to the section id,

( ay )' :::• + ,;-c =r 2 •

24 ON TIIE FORM OF TUE YOUSSOIRS OF A CONVERGENT ARC'H OR VAULT.

Now this may be written,

( be)' y--z• a

;:;+ (;)' =L

whence bdb' is an ellipse, whose axes a~e l'espectively bb' and r, its centre being in the middle point of bb'. Hence in this case the rules for the construction of the centring, and of the fronts and backs of any voussoirs, are the same as those above given. The equation to the surface of contact of two contiguous youssoirs

will be . xytanq:, x'(rcosq:, +c) tan</,

:::-rsm</J= --a- - a~ ;

and if we suppose this to be cut by a plane which is perpendicular to GP, and at a distance r' from G, the equation to the curve referred to the analogous axes will be obtained as before; viz.,

The equation to the cutting plane is,

zsinq, + ycosq:, = ,, + ccosq:,.

The equation to the projection of the curve on the plane xy is,

x•(r cosrj, + c) sin</, tanrj,

a•

xy tanq:, sin</,

a ycosq:,+r'-rs,n'q:,+ccosq, = O.

And the required equation,

x' (r cos</, + c) sinrj, tanrj,

a'

xysin 2 <p tan<p

a

And as this equation is of the form,

y sinrj, cosq:,+r' -r sin •q:,+ccosq:, = O.

Ax' - Bxy - Cy + D = O,

it admits of the same discussion as in the former case, the same inferences will follow from it, and the same rules be founded upon it.

The equation to the projection of the horizontal joint through P on the cutting plane will be

ay = x (c + rcosrj,) sinrj, +a f (r' + c cos</:,) cotanq:, - rsinrj, cosq:,j.

The above equations will, of course, reduce to those discussed in the text if we write c == 0.

J. F. T.

ERRATUM,-P,1gc 12, line 121 omit the words ,; at right auglt:s.' 1

Fig 5

a

r: -~, " ' ' ' ' ' ' ' ' ' : is :

X

' ' ' T

PAPER IV.

NOTES UPON TIIE CONSTRUCTION OF BUILDINGS AT G!DRALTAR WITH TAPIA.

COMPILED BY HENRY c. JAGO, CLERK OF WORKS, R.E.D.

FORWARDED BY COLONEL STEHELIN, C.R.E., GIBRALTAR.

In the empire of llforocco the walls of fortifications and other substantial buildings, and even tl1ose of dwelling houses, are made of a composition known by the name of " tapia," which is extremely durable, not liable to splinter, and consequently well adapted as a substitute for masonry in works of defence.

The Moorish Castle at Gibraltar is a good specimen of this style of building, ha\ling stood for upwards of 1,100 years with little sign of decay from age. It was rnoreoYer exposed to the fire of the enemy's batteries for three years, during the great siege, without injury to the walls, except the small indentations made wherever a shot struck.

The real art of making tapia has apparently been lost in Gibraltar, for the modern attempts have produced a very inferior composition, scarcely better than well-rammed earth.

Under these circumstances, application was made to the Emperor of Morocco, to send masons to Gibraltar to instruct the Engineer Department in the true composition and manufacture of tapia, and the method of building with this material; and the Emperor, as will be seen by the annexed letters, sent two of his best workmen over to the garrison, under whose instructions a traverse, (33 ft. 10 in. by 13 fl) and the merlon of a battery were constructed; and the process is explained in the accompanying memorandum.

)IElIORANDUll RELATIVE TO THE PREPARATION OF, AND MODE OF BUILDING

wrrn TAPIA, AS EXECUTED UNDER ·rnE IMMEDIATE DIRECTION AND SUPER­

INTENDENCE 0}~ MOORISII MASONS, IN TJIE ERECTION OF A TRAVERSE AT TIIE

GRAND BATTERY AT GIBRALTAR: COMPILED BY l\1R. HENRY C. JAGO, CLERK

Of' "'ORKS,

:MATERIALS USED.- Surface soil, sand, and pure clay arc rejected as useless. ,1arl of' a dark red colour, containing oxide of iron, gypsum, ~olcanic lime, sand and some salt not clearly ascertained by the tests used, as found in the red sand pits at Gibraltar, was in this case the material selected, which, with lime, finely slacked, and broken stone, or loose shingle from the quarries, were used by the :Moorish masons in the composition of tapia. Round pebbles or bench shingle ure inapplicable. The debris arising from the destruction of old masonry walls, and the refuse of the mortar yard or lime kilns, are good and useful materials.

D

26 ON THE CONSTRUCTION OF DUILDINOS WITH TAPIA.

PROP0RTIONs.-About 25 cubic ra.rds were mixed at once, 1iud in the follow-ing proportions : viz. •

Marl ................... . ........ cubic yards 13 Shingle.......................... 3 Limc--rcfuse . . . . . . . . . . . . . . . • . . . . . . 2¼ Lime . . . . . . . . . . . . . . . . .• . . . . 6½

Should the lime-refuse not be available 2 cubic yards of shingle and half a yard of lime may be used instead.

PREPJ.RATION.-The marl, shingle, and lime-refuse are spread in a bed about 1 foot 6 inches in depth i the lime, haviug been carefully slacked, is then evenly s1>read oYer the surface of the mass, aud a considerable q_uantity of water is poured over the whole, after which the workmen commence at one or more sides of the heap or bed, and cut and turn it over with picks and shovels. Should any portion appear dry, more water is added; and t,his process of tw·uing over nod watering is continued until the whole of the ingredients are thoroughly mixed. The requisite amount of water and the state of' the tapia are tested by compressing a portion in the hand; if with moderate pressure it will afterwards maintain its form, it is fit for use, but if it fall to pieces it is too dry, must be again turned ovet\ and more water added; if, however, it gives too readily to the pressure of the hand, it will be too soft, and more dry material must be added to stiffen it. About 1,000 gallons of fresh spring water were found neces­sary to mix the 25 yards of tapia. After being thus prepared, the whole mass must be allowed to stand for a day or two, and on no account is it to be used until the lime is completely cold.

EXECUTION.-In the erection of buildings composed of tapia, the work is carried up in coffers, or casings of 3~inch planking, the sides being placed as far apart as the thickness of the walls is proposed to be. These coffers in the pre­sent instance were kept together by framework, composed of sleepers, uprights, and caps, all of deal 4¼ inches wide by I¼ inch thick, morticed and tenoned, placed at distances of about 2 feet 9 inches apart. Care must be ta.ken that the sills of these frames are set perfectly level, and the uprights perpendicular, or difficulty will arise in carrying up the succeeding courses.

The sides or casings of the coffers were of 3-inch deal, 9 inches wide, wrought on the inner faces, and the edges shot; three of these in depth were bolted together with ~-inch round iron bolts, placed at distances of about 5 feet apart, to form each side. 'fhe bolts bind the deals together and prevent their warping.

In laying the sleepers for the first course of ta.pin, each sleeper being plac~cl perfectly horizontal is cased with rough stone-work, forming a rough drain, to take the pressure of the tapia off the sill or sleeper, and leaving them free for removal to an upper course. After the first course, grooves are cut in the upper surfaces of the courses of tapia, as the work proceeds, to receive these sills or sleepers, and small flat stones are laid over them to facilitate their removal. To cut the grooves a miner's pick with a curved head, 1 foot 6 inches loan-, and a helve 2 feet long, is used. Old pick-axes were altered for this pw·pos;, and were found to answer extremely well. . The framework ha~ing ~cen thoroughly secured, the prepared tapia is thrown m between the plankmg m layers about 9 inches thick, and as many men as

ON THE CONSTRUCTION OF BUILDINGS WITH TA l'IA. 27

cnn get into the spnce between the planking (being each provided with a rnm­mcr) commence ramming the material. Ordinary field-work ramming is alto­gether useless. 'l'he rammer is raised nearly to the level of the shoulder and brought down with all the force the man is capable of exerting. The ramming is done by word of command, so that nil the rnmmers come down at the same time, the words used by the Moors being, " Y Allah, zah ! " (Y Allah means " To God," or 11 0, God," n.nd znh, used in bringing down the rammer, means 11 strike together.") This is found to be the most laborious part of the work, and must be strictly attended to. After the ramming has been continued some time, the tapia will have been worked into a soft paste; a small quantity of coarse broken stone is then e,·enly spread over the surface, and the ramming again proceeded with; this ramming and supplying broken stone is continued until the mass has become tough, and no longer adheres to the rammer; another layer of tapia is then spread, and so on, until it has reached the top of the casing or coffer.

To the 25 yarcls of topia originally prepared, 3 yards additional of coarse stone were used during the ramming.

The compression of the material was about three inches in the original depth thrown in of 9 or 10 inches. ·

Two days should elapse before the frames are removed ; an earlier removal may injure the whole work. After the framework has been taken away the filling in of the centre of such a construction as a traverse may be proceeded with at once ; for this purpose earth, debris from old buildings, and coarse shingle l\re used, having about half a cubic yard of lime riddlings, mixed with 9 cubic yards of earth; this is first in·~pared by turning and watering, similarly to the preparation of the tapia, ao·d is afterwards filled in and rammed in a similar manner.

The eaves-course of the traverse was formed of three courses of Malaga bricks, laid in mortar, and projecting 3 inches from the face of the traverse.

The top was formed roughly with the tnpia, and covered with about 3 inches of common mortar, into which small dry shingle was beaten until it became of considerable rigidity.

The whole surface of the traverse was afterwards plastered with a thin coat of plaster prepared as follows :-Lime, taken fresh from the kiln, was carefully slacked and sifted through a fine sieve, great care being taken that no particles remained unslacked, and was mixed with clean sharp sand finely sifted, in the proportion of one of sand to ten of lime, with as much water as worked them into a very stiff paste, in which state it was left for at least four or five days before it was used.

'l'he mode of treatment and the materials and utensils used in the construction of erections in tapia are so similar to those used in the erections of II pise," that attention is directed to the article on "Pis€,1' in II Nicholson's Architectural Dictionary." London: J. Barfield, 1819.

R. E. Office, Gibraltar, 16th May, 1860.

PA PER V.

ACCOUNT OF TIIE 0PER.\TI0" OF BLASTING WITII LARGE C11rnaES A'.f

THE QUARRIES AT HoLYilEAD IN NOVEMBER, 1860.

BY COL. HAMILTON, ROYAL ENGINEERS,

MINUTE BY THE INSPECTOR GENERAL OF FORTIFICATIONS,

In Vol. II of our Professional Papers, New Series (1852), will be found a long account of the mining in the Holyhead quarries up to that period.

Similar operations have been carried on there ever since, with much judgment and effect, by the Contractors, Messrs. Rigby, aided by their efficient Resident Engineer :Mr. Cousens.

Through their polite attentions, Colonel Hamilton, Royal Engineers, wns enabled to witness a recent large explosion, and to collect information which is well worthy of being recorded, and which he has embodied in the following report.

REPORT ON TJIE EXPLOSION OF 12,000 lbs. OF GUNPOWDER IN TITE

Q.u ,\RR1ES AT HOLY.Iff,AD, ON TlIE 24th NOio'EM.DER, li'WO.

Rv COLONEL HAMILTON, R.E.

Royal Engineer Office, Manchester, 30th November, 1800.

8TR, In accordance with the instructions conveyed in your letter dated 22nd

inst., I attended to witness an explosion of gunpowder at the quarries of tho harbour-works at Holyhead on the 24.th inst., and have the honour to report, in reference thereto, as follows 1 viz. :-

'l'he quarries, opened and worked by :Messrs. Rigby, Coutraetors for the harbour-works, are situated on the declivity of the Holyhead Mouutain, at nbout 1,500 ycls. distance from and in rear of the land end of the brcnkwatcr the portion thereof, 120 feet by 40 feet, arnl 90 feet in height, on this occasioll opcn.tcd on, was foL'llltd of quartzose schh:;t, extremely hard and weighing a.bout.

ON TllE OPERATTON OF BL.\STING WITH LARGE CIIAilGES AT IIOLYIIEAD. 29

I J ewt. to the cubic foot, stratified in lines extending from N.E. to S.W., a little overhanging to S. E., but nearly vertical, with numerous joints in that and other directions throughout the whole mass.

An entrance gallery, 5 ft. 6 in. by 3 ft. 6 in., was driven from the face of the rock, commencing at a height ot' 12 feet above its base, wit.ha vie,v to gain an efficient line of tamping resistance, a favourable joint in the line of strata having been taken advantage of to the extent of 34 feet, where a shaft, 3 ft. 6 in. by 3 ft. 6 in., was sunk to the depth of 14 ft. 6 in.; from this level galleries, 5 ft. 6 in. by 3 ft. 6 in., were driven right and left, the former to the exte:nt of 49' 9" and the latter 56' 6", with a length of 43' 6" of headings and chambers of similar dimensions, as illustrated in the accompanying plan and elevation. The galleries, shafts, &c., were worked out by blasting, necessitated hv the hard nature of' the rock; and the increased size given to these communications above that generally adopted was with a view to enable the miners to strike with more freedom and effect, the extra excavation being more then compensated by the facility of working. The chambers were formed by slightly enlarging the short return-headings, and were placed from two to three feet below the level of the ground or rail line in front of the quarries, to ensure the bottom of the face noted upon being well lifted, as want of attention to this particular before a former explosion led to considerable subsequent labour in removing a portion of stone left standing.

The gunpowder used wns similar to the fine grain government powder, its strength having been previously tested by projecting with a I½-oz. charge a 68-lb. shot from a mortar at an angle of 45° to the distance of 480 feet; the charges were placed in canvass bags well coated with tar, 2,000 or 3,000 lbs. in one bag, and the remainder in smaller bags, and so respectively lodged in each chamber.

The tamping was executed throughout with a sort of stiff red clay obtained in the vicinity, used in a slightly moist state, well rammed up to the entrances of the chambers, and close to the bags of gunpowder, merely leaving a small air space round the latter, and was continued to the mouth of the gallery in the face of the rock: it apparently answered its intended purpose admirably.

The battery employed to fire the charges was that known as Grove's. It had 32 cells, and platinum plates, 8 in. by 6 in., in nitric acid, in porous cells sur~ rounded by diluted (G to I) sulphuric acid; it was placed on the top of the cliff, and directly in rear of the line of chambers, 300 feet distant from the upper edge of the former; two copper wires connected the battery with ench charge, extending from the latter through the galleries directly up the face of the cliff and on to the cells, where the four positive were united, as well as the four negative. This method is considered by the Resident Engineer of the works much safer than using only one positive wire through all tl1e charges and one negative in return. To the extremities of the copper wires at the charges were attached platinum wire about¼ inch in length, protected by a wooden block, round which block a small bag of fine or sporting powder was tied and introduced into the lnrge bags of powder before-mentioned.

'!'he total quantity of powder used in the explosion was 12,000 lbs. placed in four <•barges amounting respectively to 4,000, 3,000, 2,300, and 2,700 lbs., with lines of least 1·csisto.ncc 20 fc.:et, 32 feet, 22 feet, a.ud 24 feet 6 inches, as shown

30 ON TIIE OPERATION OF BLASTING WITJI L.\.ROE CTIARGES AT noT .. YTJEAD,

on the drawing i these respective charges wero not calculated by nny specific formula founded on the lengths of the lines of least resistance, but a certain number of pounds of gunpowder J)Cr ton of rock to be removed wns allowed, nccording to the particular features and tenacity of the portion t? be acted _on (in the present instance 1 lb. of gunpowder to 3 tons of roe~) ; this ca~culation was based upon the experience gained from numerous previous explos10ns of a similar character carried out at different parts of the quarries. In some cases 1 lb. of gunpowder was found sufficient to remove only two, in other cases it has pm·red adequate to displace four tons of stone.

Shortly after the hour appointed (12 o'clock) the mines were fired by the Contractor's Resident Engineer, who nmaincd at the battery, on a signal from Mr. Rigby, with most successful results: the rock a little above its base was seen to bulge slightly outwards and then tumble to pieces, emitting much smoke, and the superincumbent mass gently sliding down, separated into various sized blocks i a perfect volley of srnnll stuff, mostly the tampiug, shot horizontally along, close to the ground, directly in front of the face of rock to a distance of about 250 feet, covering the surface with a coating of fine damp clay separated into small particles like sand; no stones of any magnitude ,~ere thrown out beyond the general debris, which was confined to a width of 125 feet from the original face of the quarry, as shown in the section.

The total quantity of rock removed was about 40,000 tons, which gives 3} tons to the pound of gunpowder used.•

'l'he miners were but little impeded by wet or damp, the gallery was driven with a slight inclination upwards, to allow any water met with to find its way out: whenever damp holes had to be fired, pitched bags or cases, capable of holdillg 3 to 5-oz. charges, were used ; the smoke from the firing of the blasts and foul air were removed by a rotatory blower worked by a boy at the mouth of the heading, and a canvass 11ipe conveyed the fresh air to the chambers.

The powder was brought to the mouth of the gallery in casks (containing from 50 to 100 lbs.) and there emptied into canvass bags capable of holding 50 lbs.: these bags were then passed from hand to hand by men placed at intervals in the galleries, to the respective chambers, where they were discharged into larger bags previously lodged there, to the extent required, after which some old powder cask sackings were thrown round and over them.

•The report on the effect of a similar explosion in January, 1857, printed at page 140, Vol. VI. of this Series, shows that 7 ½ tons per pound of gunpowder were then brought down, or nearly double the quantity removed by each pound on this occasion; and on reference to the accompanying plan it will be observed that if, instead of the charge of 4,000 lbs., a smaller one had been employed, the effect would probably still have extended as far as the joint at that end, and also that a slight addition to the charge of 2,700 lbs. at the other end would have caused the fall of all the portion as far as the recess, which is described as II much shaken." It may also be remarked that the cliff brought down in January, 1857, was 25 feet higher than that here described, also that the strata of the former were horizontal, whilst those of the latter were vertical, and, on the other hand, that the blocks forming the debris of the htter were smaller, aud more suitable for building, than those of the former: it is evidently therefore difficult to fix any rules for cletermining the quantity of powder required, especially where hidden joints exist which limit its effects.-ED.

ON THE OPERATION OF BLASTING WITll LARGE CHARGES AT IIOLYIIEAD. 31

Tho clay for tnmping was brought to the mouth of the mnin gnllcry in waggons, and wheeled through it on planks to the shaft, where it was thrown down, and conveyed from the bottom thereof in a similar manner to the headings. '!'his method was found to require less time and labour than any other known to the Engineer. 'l'he whole of the tamping was performed in 42 hours by 25 labourers.

The copper wires leading from each charge were, throughout their course in the tamping, lapped round with calico and tar bands, great care having been taken when tamping about them. This method was preferred to that of using wooden casings, and gave much freedom and ease in turnings at the angles and bends in the headings.

The cost of the powder (12,000 lbs.) used in the oborges amounted to £300, and that of the canvass bags in which it was placed, including the tarring thereof, to £4 4s. 'l'he cost of the battery wa.s £41 10s., nnd that of the wirea connecting it with the charges £10 10s., made up as follows, viz.:-

GROVE'S BATTERY. £ s. d.

32 porous cells at 2s. 8d .............................. . 4 :; 4 32 zinc plates at 2s. 6d ..........................•...... 4 0 0 32 platinum ditto at 15s ............................... .. 24 0 0 32 gutta percha troughs at 2s. 6d ........................ . 4 0 0 :Mahogany case for box, quicksilver, poles, &c ............. . 2 14 8 2¼ gallons nitric acid to fill the cells at 18 8d .............. . 2 6 8 /, gallon sulphuric ditto at 6s. Sd. . .................. . 0 3 4

£41 10 0

WIRES.

8 copper -wires from the battery to the charges, including calico lapping nod tar bnnds :-

8 x 500 ft. =: 4,000 ft., and 800 ft. of wire weighing 28 lbs., 4,000 ft. = 140 lbs., at ls. 6d., cost £10 10s.

The time occupied in driving the galleries, shafts, &c., was about 9 mouths, the rate of progress averaging 1 foot per day of 24 hours, and 8 miners working; the cost being as hereafter detailed, viz. :-

£ s. d. 25s. to 26s. per foot of galleries driven, according to hard- j 267 15 0

ncss of rock, 210 feet, at 25s. 6d ................... .

Smit!q:t ;:~~u~",;y;~ a~ai0~er _w~ek) k_eeping·t·o·o·l~ .'~.~rd~r'. j 18 0 0

Powder used in blasting (3 lbs. per foot), 210 X 3 = 630 at 6d. 15 15 0 l inch of fuze per foot = 210 at 4d. .. .. .. .. . . . . . . . . . . .. . . 3 10 0 6 lbs. of candles per week, 36 X 5 = 216 at 8d. . . . . . . . . . . . . 7 4 0 30 bags or tarred cases at 9d. .. . . . . . . .. . .. . .. .. .. .. . . . . . 1 2 6

£313 6 6

Thus it would appear that 40,000 tous of stone were procw·c(l at an expense of £600 lOs. 6d., or about {c\. per ton.

:12 ON THE OPERATION OF BLASTIXG wrrn LARGE CHARGE:-! AT lIOLYIIEAD.

I witnessed the explosion from n point 150 yards in front of tl1c cliff : the report was not loud, it resembled the s01md of , ,cry distant thunder. On tho whole the operation was a satisfactory one to l\ir. Rigby and his nssi5tant engineer, l\Ir. Cousens, to both of whom I nm much indebted for the free nnd unreserved information they readily afforded me. The latter gcutlcma.u favoured roe with the plan and clcYation already referred to in this report.

I have the honour to be, SIR,

Your most obedient humble servant, R. G. HAMILTON,

Colonel, Com. Royal Eng.

REMARKS BY THE INSPECTOR GENERAL OF FORTIFICATIONS,

It would be presuming to venture to criticise a proceeding conducted with so much intelligence and success, and after years of constant practice in work of the same character; but it might be worthy of consideration whether an important saving in time, expense, and trouble, might not have been effected, in the driving of the passages, loading the mines, &c., by suppressing the shaft in the interior, 14 feet in depth, altogether.

Had the galleries been so wet as to require baling or pumping out, the incon­venience of the shaft in the interior would have been greatly increased.

I should myself ha,·e started from an excavation about 3 feet under the surface at the foot of the cliff, instead of commencing at 12 feet above the ground; nnd have worked from that level, with a slight rising incline, on the lines laid down on the plan, and have placed the chambers at the same sites and levels as shown on plan and section.

" ' ith the entrance thus sunk and well tamped down to the solid ground, with such large charges, and long and tortuous galleries, I should confidently have expected as good results, notwithstanding the appearance of the tamping being liable to be blown out, which I do not think it could have been inde­pendently of the general effect. But all this is reasonable matter of opinion.

33

PAPER VI.

JOURNAL AND REPORTS ON THE OPERATIONS OF THE ROYAL ENGINEERS

AT THE SIEGE OP JHANSI.

BT THE LATE LIEUT. COL. T. FENWICK, AND MAJOR EDWARDS, ROYAL ENGINEERS.

JOURNAL 01' OPERATIONS OF CENTRAL INDIA FIELD-FORCE IN FRONT

OF JBANSI,

25th March, 18~8.-The 1st Brigade arrived at Jhansi at 7 A.M., 25th March, after a march of 22 miles, and found the 2nd Brigade investing the town .. About 4 P.M. I accompanied Major Boileau, Commanding Engineer, to the front. A mortar battery was established on the eastern side of the town about 1,800 yards from the citadel. (See Plan.)

26th March.-Sent up a working party of Royal Engineers at 5 A.M., under Lieutenant Gossett (1 non-commissioned officer and 12 men), to lay platforms for two 10-in. mortars. Sufficient material was not furnished by the Ordnance. At 7 P.M. commenced laying platforms for two 8-in. mortars. They are of Bombay pattern and answer admirably. They consist of 3 sleepers, with a pivot in front, and a frame of 8" X 8" timber, with guide-pieces of iron, between which the mortar recoils. Also commenced forming a parapet with an embrasure for an 18-pr. gun to breach an advanced or salient work at the south-east angle of the fort, forming part of the town wall. (See Plan.)

27th Marcb.-The two 8-in. mortars were removed to the right front. A battery was ordered to be erected for them and the 8-in. howitzer. I consider that the howitzer would have been more effective in the first position proposed. It is now on a lower level by 30 feet, thus losing the advantage of command. Also a sand-bag battery for two 18-prs. was commenced on the knoll to the left, to counter-batter the enemy's guns.

28th March.-Tbe 18-pr. opened fire at about 8 A.M. The first two or three rounds missed the white tower about 600 yards distant. A small bill in advance was occupied as a rifle trench during the night.

29th March.-The mortar and howitzer batt~ries were completed during the night. After a few hours' firing the position of the howitzer was changed by the Artillery officer.

30th March.-Tbe 18-pr. began to have an effect on the wall of the mound. Batteries still firing. Scaling ladders were ordered to the front. The enemy stockaded the breach with trees during the night.

E

34 OPERATIONS OF TIIE ROYAL ENGINEERS AT TIIE SIEGE OF JHANSJ.

31st Marcb.-An alarm of enemy advancing in force from the eastward. Th~ 2nd Brigade and part of the 1st went out towards the Betwah River. 1st Briga~e shifted camp close to 2nd Brigade, and returned about 9 A.M. to nearly its original position.

1st April.-Euemy advanced during the night and attacked at daylight; they were repulsed after two hours' fighting, with a loss of 17 guns and 4 elephants, and were driven across the Betwah.

2nd April.-The assault of the town in four columns, about daylight, was determined on.

3rd April.-Assnults of the breach at the Mound and of the Rocket Tower by escalade took place at daylight with success. At the right attack 2 officers of Engineers of the Bombay service were killed, and 1 wounded. This attack failed in the first instance.

4th April.-Mortar shelling the fort. Infantry tnking gradual possession of the town.

6th April.-The citadel was evacuated before day-break, and the British flag was hoisted on a tower.

(Signed) T. FENWICK, Captain,

Thermometer 103° at 10 A.M. Com. Royal Engineer and Field Engineer.

MEMORANDA RELATIVE TO JHANSI.

Jhansi, a town" in Bundlecund (Lat. 25° 28', Long. 78° 38'), is situated amidst tanks and groves, and is surrounded by a loop-holed bastioned wall from 22 to 26 feet high. The gateways are all flanked, and were all built up inside by the enemy. Several guns were mounted on the ramparts.

On a rock overlooking the town is the fortress. There are 6 gates, one within another. On the east side it is perfectly impracticable. On the south side are 3 towers 50 feet high, of good masonry, connected by curtains; there is also a second or lower line of ,works along this face. The tank is close to the south­west tower.

On the west side of the fort there are 4 towers, and an advanced work on a lower leYel, containing a well of good water.

On the north side there is a double line of works with circular towers. In the interior there is a large square tower and a palace of four stories, with

other buildings. There are some casemates in the north face and a gunpowder manufactory. 27 guns were found in the fort and town.

About 600 yards from the fortress, on the south side, are three ridges of hills nearly as high as the rock on which the fortress stands.

'l'hese formed the position of the left attack, and of the following batteries:­No. 1 Battery of two 18-prs. to counter-batter. No. 2 Battery of two 10-in. mortars to shell fort and town. No. 3 Battery of one 18-pr. to breach town-wall at Mound. No. 4 Battery of two 8-in. mortars and one 8-in. howitzer to shell fort and

defences.

(Signed) T. FENWICK, Captain,

Com. Royal Engineer aud l<'ield Engineer.

Ol>ERATIONS OF TIIE ROYAL ENGINEERS AT THE SIEGE OF JIIANSI. 3,5

REPORT. SIR,

. I havo the ho?our_ to forward a copy of my report to the Commanding Engineer, Central India Field-Force, of the assault of Jhansi from the left attack in which the 21st Company Royal Engineers formed the ladder party, and working party for making a lodgment at the breach. I beg to report that the Company behaved very well and steadily on this occasion, and I have the honour to request that you will bring their conduct to the favourable notice of the Inspector General of Fortifications.

I have the honour to be,

SIR, Your obedient servant,

(Signed) T. FENWICK, Captain,

The Com. Royal Engineer, India. -

Com. Royal Engineer and Field Engineer, Left Attack.

REPORT ON TITE ASSAULT OP THE DEFENCES OF THE TOWN OP JHANSI

FROM THE LEFT ATTACK, AT DAY-BREAK, 3rd APRIL, 1858.

To carry out the Division orders of the 2nd April, 1858, the 21st Company of Royal Engineers paraded at 2.30 A.M., and were marched up to the valley in rear of the batteries of the left attack, where they were told off to their respective ladders by Lieutenant Edwards, Royal Engineers ; they then moved silently up the valley in rear of the howitzer battery, and the ladders were deposited on the reverse slope of the small hill on which the advanced rifle pit was formed. The party was handed over to I,ieutenant ,vebber, Royal Engineers. The head of the column intended for the escalade was formed in rear. The column, under Colonel Lowth, 86th Regiment, intended to assault the breach, formed as

nearly opposite the salient of the mound as possible without attracting the notice of the enemy. On the signal being given (viz., 3 shot from the 18-pr. breaching battery), the columns moved off, and when about 150 yards from the rocket tower, the enemy commenced a brisk fire on the esca.lnding party, of mus­ketry, rockets, &c., wounding two men of the Royal Engineers; and on the party getting close to the wall threw down stones an<l. bags of charcoal, &c. The ladders were at once raised, and placed against the wall of the rocket tower, and the enemy driven from it. Lieutenant \Vebbcr conducted and placed the ladders in a most satisfactory manner, and the conduct of the men was admirable.

The column for assaulting the breach moved swiftly up the glacis, and crossed the ditch at a point where it had not been entirely exca,·ated, and ascending the breach with a cheer, obtained possession of the Mound. As soon as the troops had moved down into the town, the Royal Engineers, under Lieutenant Edwards, commenced and formed a breastwork (embracing the guns captured there) under o. fire of guns and gingals from the fort. In executiug this senice two men were wouncled.

3G OPERlTIOXS or TIIE ROio\L F.NGTNF.ERS AT TTTE 8TF.GE OF JJT \NSl.

My thanks are due to Lioutcnnnt Edwards for the en_ergy and coo\ncs_s with which this service wa.s carried out. I beg also to bring to your nohce the services of Lieutenant Gossett, Royal Engineers, who accompanied me with o. amo.11 party down to one of the town gate~, which the enemy hnd bnilt up with stones nnd earth, which were cleared away and the communication opened.

T. FENWICK, Captain,

Commanding Royal Engineer, Bombay Presidency, Field Engineer, Left Attack.

Nominal List of Men wounded.

2nd Corporal Johns . . .. . . • • . . • • . • • . ....••.•.•• Sapper T. D. Smith ........................... .

G. Moore ............................. . R. Mc.Lay .... ............ ........... . H. Ramsey .............. .. .

Slightly. Severely. Severely. Severely. Severely.

NOTES ON THE ASSAULT, BY 1\1AJOR EDWARDS, ROYAL ENGINEERS.

Two assaulting columns were formed at the right attaek, and two at the left, all being under the direction of Major Boileau, 1\Iadrns Engineers.

The columns at the right attack were directed by Captain (now 1\fojor) Browne, an offieer of the Madras Infantry, who was in command of the native company of l\Iach-as Sa1Jpers and Miners.

The assaulting columns from the left attack were under the direction of Captain Fenwick, Royal Engineers.

The two escalading columns from the right attack were directed on either side of the Orcha Gate : the ladder party of that on the right was com­m::mded by Lieutenant Meiklejohn, Bombay Engineers, and the other ladder party on the left by Lieutenant Dick, Bombay Engineers. Each party was provided with six. or seven ladders, carried by Madras and Bombay Native Sappers. There were two different kinds of ladders, some being similar to those used by us, only perhaps larger, and others being the bamboo ladder used in India. (The bamboo ladders are made of two long bamboos, 30 feet in length, with thin tamboos lashed at proper intervals to form the rungs).

The column on the right found the wall about 25 feet high, and that on the left nea'rly 30. In each case only three ladders were got to the front. Lieut. l\Ieiklejohn was the first up the ladders with his party, and was dragged oYer the wall and cut to piece!. Lieutenant Dick mounted his ladder first, n:ncl on m-riving at the top was shot through the head, falling dead at the foot of the ladder: the ladders were then immediately upset, and every effort to place them again was unavailing. The native Sappers by all accounts behaved most nobly, and their severe loss testifies to this.

TOWN

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A1\ \TACJ,

OPERATIO~S OF TIIE ROYAL ENGINEERS AT TIIE SIEGE OF JIIANSI. 37

The dispositions of the Engineers for the two columns of the left attack were as follows:-

That on the right, under Colonel Lowth, 86th Regiment, was directed to storm the breach in the town wall ou the ~found ; it was accompanied by 25 Sappers of the 21st Company, Royal Engineers, under Lieut. Gossett, R.E., to assist in removing any obstacles, and, after it was tnken possession of, to throw up au entrenchment on the Mow1d, so that in the event of our not being able to keep possession of the town, we might be enabled to retain the Mound, which com­manded all the surrounding part of the town. The party attacking the breach did not meet with much resistance, as a hea,·y fire had been kept up throughout the night upon it ; but the enemy had stockaded it so strongly that great difficulty would have been experienced in entering if a determined resistance had been made. The greater part of this column proceeded along the town-wall to their right, driving the defender:,; awa.y from it, until they came to where the columns of the right attack had failed to escalade, thus enabling those colWlllls to replace their ladders and enter the town.

The left assaulting column of the left attack, commanded by ~Iajor Stuart, 86th Regiment, was cl:incted to escalade the wall in the ,alley between the Mound and the Fort.

'l'o effect this object it was proYided with seven laclders made somewhat of the same pattern as those now used at Chatham, but I think they were rather broader and heavier. These ladders were carried by 50 Sappers of the 21st Company, Royal Engineers, under the command of Lieut. "'ebber, R.E. This colwnn was brought up to within 350 yards of the wall }Jre,·ious to the attack, in the dark, aucl moved off in capital order when the signal was gh-en. ,Vhen within 150 yards of the wall the party was rather disordered by having to pass over some rough ground, and Lieutenant ,vebber halted and formed them up in good order, under a smart musketry fire; they consequently arrived at the foot of the wall in perfect order, and the whole of the seYen ladders were placed at the same moment, chiefly around a small circular tower. The wall was here 27 feet high, and loophol~d. The enemy had nrepared large masses of stone along this 11art of the wall, which they had placed so that they could push them off the wall on to the assailants at the foot: this they did, and broke some of the rungs of the ladders : they also fired rockets through the loop-holes and threw over earthen pots full of powder and some offensiYe composition. The assaulting party, headed by Lieutenants Dartnell, 86th Regiment, and ,vebber, soon gained a footing in the Tower. Lieutenant Dartnell was first on the wall, and receiYed a great many sword cuts before Lieutenant ,vebber (who was prevented from being as soon in consequence of two rungs of his ladder being broken by a large stone) could come to his assistance. After considerable resistance a footing was gained, when the enemy soon vanished.

The four columns then moYed on through the town towards the palace, all experiencing- more or less resistance, that on the left suffering seYere loss from having to pass under the fire of the Fort.

Besides the men employed in making the entrenchment on the Mound, 1mrties of Sappers were employed with the columns in the town, some to open the gate­ways, some to break open the doors of houses occupied by the enemy, and others

I

J

I I ·

38 OPERATIONS OF THE ROYAL F.NGINEEitS AT TIIE SIEGE OF JilANSI.

in opening up comruunicntious between houses, in erecting blinds with old fur~ niturc nud anything that could be procured, across streets which were looked into by the Fort, which enabled the wounded to be carded off unseen. Corporal Slenvin, Royal Engineers, behaved so ,vell in making n blind across a street, down which there Wll.S a very heavy fire, that Sir H. Rose gave him the Victoria Cross.

I nm of opinion that to cscnlacle a wall 27 feet high, except as a surprise, is an operation that may be considered impracticable in war, with anything like a determined enemy, unless you assault with a front of from 60 to 100 ladders.

In this instance the assaulting column was composed of chosen men of the 86th Regiment, at that time perhaps as fine old soldiers as any in the world, and they had been 18 years in India.

The ladders made in lengths, after Sir C. Pasley's pattern, proved the best on this occasion, but the bamboo ladders, if properly constructed with rungs firmly lashed, are lighter and quite as strong; in general, however, I think the former are the best, as they are put together more quickly, and are less likely to fail, besides being capable of being shortened at pleasure.

JAMES EDWARDS, Major, Lately Commanding 21st Comp., RE.

PAPER VII.

REPORT ON TWO BRIDGES CONSTRUCTED OVER THE GOGRA AND CHOWKA

RIVERS, IN JANUARY AND FEBRUARY, 1859.

BY LIEUTENANT HARRISON, lloYAL ENGINEERS.

BRIDGE OVER THE GOGRA RIVER.

The river Gogra between the villages of 1\Inllapoor and Rajhpoor, which is that portion to the west of Buraech, and situated between that town and Khyra• bad, may be said to be of an average width of one and a half miles; for the main stream is so split up into numerous channels, with large sandy islands and banks of mud which are perpetually changing their appearance, that the high water­mark embraces a very wide extent.

The place selected for a bridge, both on account of its being the shortest road from Seetapore to Buraech, and n.lso because the features of the river presented fewer difficulties to be overcome there than elsewhere, vrns close to the deserted Fort of Chclari, which afforded some material for the construction of the bridge.

ON BRIDGES CONSTRUCTED OVER THE GOGRA AND CHOWKA RIVERS, 39

The riYer is divided at this point into two channels by an island about one and a quarter miles in extent, one being fordable and about 60 yards across, and the other varying from 1 foot to 30 feet in depth, and being 427 yards in breadth at the narrowest part.

'l'he steep bank on the Buraech side of the smaller stream was cut down, and a road made with fascines and small brushwood on both sides of the water, as well as across the island. 'l'he Delhi Pioneers, who furnished a daily working party of about 500 men, were employed in making this road over the island, cutting down the high bank on the Seetapore side of the river, and making strong ghats on both sides of the large stream, as well as a roadway of bamboos where the depth of the water permitted.

In the meantime a few carpenters were employed making anchors and piles, and some coolies in making rope; and every effort was made to collect materials, ,'1Z., timber, saws, jute for making rope, iron for nails, &c., &c.

It was not till the 17th January, 1859, that, by the help of the Deputy Com­missioner of Buraech, who sent up 100 carpenters and sawyers from Bairam Ghat, the bridge can be said to haYe been commenced: on that date the first plank was sawn, and the first boat fixed in its position, and from that time the work went steadily on till its completion on the 7th February.

The number of boats used was 41, their width varying from 9 to 16 feet, and their length from 20 to 30 feet. The bays were 12 feet wide. The roadway was made of 2-inch planks and was 13 feet wide, the planks being laid trans­versely on 5 baulks of an average size of 7 in. by 5 in., which overlapped each other about 2 feet, and were bound firmly with rope. The planking was spiked with 7-in. nails made by the natives from arms taken from the rebels. The whole road was covered with straw and horse-litter.

'l'he total number of feet running of Baulks was,. Add fly for crossing, &c •.•...•.•.••••• , •••••••

Total length of baulks .••.• , ••

The total number of feet running of planks was .• Add 7frs for cuttings, &c .••....•..•.•.•••..••

Feet. 5 X 1008 = 5040

:: 504

(7" X 5") 5544

Feet. 13 X 1008 = 13104

655

Total length of planks ...... (12" X 2") = 13759

A hand railing of bamboo, with uprights of timber 4 feet high, was also fixed, the uprights reaching down to the bottoms of the boats, and being in size 4"by 3''•

Feet. The total number of feet running of uprights ...• 160 X 7 = 1120 Add io for spare ditto ..................... . = 112

Total uprights • .. • • • .. .. (4" X 3") = 1232

'fatal content of timber about 3,781 cubic feet. 'l'he boats were lashed together fore and aft with bamboo fascines 30 feet long,

and were secured by two anchors each, the length of each cable being about nine times the depth of the.stream, aud the anchors of natirc construction filled with bricks,

40 ON BRIDGES CONSTRUCTED OYER THE GOGltA AND CIIOWKA RIVERS,

"'hero the river was very shallow, viz., about 1 foot in depth, a break-wator was made, and a roadway constructed of 18 feet fascines of bamboo. The fascines were laid in three tiers, all picketed firmly down, the bottom tier being laid with the stream, and with intervals of 9 inches between the fa.scines, and the next tier across them, The whole length of this roadway was 91 yards, and its breadth was 18 feet.

The labour employed in making this bridge may be roughly estimated as follows, supposing the materials to be collected on the spot.

From the 17th January to 7th February, ,,iz., 22 days: 1 officer, 1 sergeant, and 14 sappers, 500 Delhi Pioneers, 125 carpenters and sawyers, 40 rope-makers and coolies, 30 smiths, and 4 7 mullahs or boatmen.

A great number of the Delhi Pioneers were employed in cutting down bamboos and making the fascines, which was a very laborious work, but answered the double purpose of destroying the fort and furthering the construction of the bridge.

The timber was obtained from Khutaee Ghat, about 20 miles up the river, and floated down; from Bounree, about 16 miles down the river, brought partly in hackeries and partly in boats; from mango trees cut down in the jungle at Chelari and Mullapoor; and also from the destruction of Fort Chelal'i itself.

As soon as the bridge was completed, elephants were sent across to test its strength, and as it sustained their weight satisfactorily it was capable of bearing anything that could be required to cross it. A raft of two large boats was made to shift easily, so as to admit of the passage of any large boats up and down the river.

BRIDGE OVER THE CHOWKA RIVER.

The position selected for this bridge was at a place called Cheemy Ghat, about 10 miles from that of Chelari. The river in many places is fordable, but hardly sufficiently so for hackeries.

The bridge was constructed of small boats about 3 feet wide by 25 feet long. The details were as follows, viz. :-Two piers were formed about 16 feet wide and 10 feet long. The number of boats used was 23, consisting of two rafts of 4 boats, and five rafts of 3 boats each 1 each raft being about 20 feet in extent. 'l'he bays were 5 feet wide. The scantling for sleepers for rafts was 22' x 611 x 411, and that for bays 12' X 6 11 X 411 • The sleepers were laid on transverse baulks lashed to the boats. The planks were 13' x 2' x 2", and the planked roadway was about 220 feet long. A bamboo hand-railing was fixed on uprights at every 12 feet, of a scantling of 4' X 611 X 4,,, The banks on both sides of the river were well cut down, and a road formed for two or three hundred yards.

The total e1.:pense of the two bridges was about 2,500 rupees.

(Signed)

February, 7th, 185?.

R. HARRISON, Lieutenant Royal Engineers,

Chelari Ghat, Oude.

41

PAPER VIII.

JOURNAL OF OPERATIONS AT THE SIEGE OF AHWAH.

By CAPTAIN CUMBERLAND, ROYAL ENGINEERS.

Ahwah is a fort of considerable strength, situated generally on a level with the country around, but rising by al'tificial means in the interior, where the Thakoor's castle or keep is situated, to a height of20 or 25 feet.

It is defended on the western face, and on the greater part of the northern, by a double line of works, the outer of earth ancl the inner line a masonry wall with flanking towers at the angles and at intermediate points. The upper part of the wall is loopholed: it is constructed chiefly of stones and mud, and is pointed with mortar; it is 6 feet thick at the foundation and 3 feet 6 inches thick at top, having a batter on the exterior face of about 2t feet. The height of the to,'i'ers is about 25 feet, and of the wall between them about 16 or 18 feet. There is no ditch. The exterior or earthen wall is about 16 feet high, aud about 30 feet thick at base and 4 at top, with a slope of 50° or 60° outside. It is also protected on the western face by a ditch about 4 feet deep and 20 feet wide, but there is no ditch on the northern face. There are fraizes of thorny brush­wood in several parts, and the same materitt.ls are used to form an abattis outside.

The eastern portion of the northern line is not so strong, having only one wall of earth 12 to 14 feet high, with masonry towers flanking it; but the tank forms a defence at this part: it is covered by a grove of trees and some temples, which are encircled by an earthen line of works from 16 to 20 feet high, with a slight ditch and abattis; in front of this, on the opposite side of the nullah, is an earthen work, open in rear, covering a temple. The tank extends as far as the eastern gate, which is flanked by two incomplete masonry towers. From this point to the south-east bastion runs an earthen line of works of considerable strength, having a command over the country of about 18 feet, and an impel'fect ditch averaging 3 feet in depth and I 0 in width, strengthened by an abattis of thorny brushwood. The exterior face is nearly vertical at the upper part, but has an average batter of about 10 feet.

'fhe defences of the southern face consist of a masonry wall 6 feet thick at bottom and 3 feet at top, and from 15 to 18 feet high. ,vithin the wall the ground is high and forms a terreplein, from which men can see over the par3pet or fire through the loopholes with which the wall is furnished throughout its whole length. It is flanked by masonry towers; and a cavalier of mud and brickwork rises behind and detached from its centre, having a command over it of about 10 feet. This cavalier, in common with all the towers which have been

F

ON TIIE OPERATIONS AT THE SIEGE OF AIIWAH.

mcutioned, is furnished with embrasures for guns. A line of aba.ttis, raised on a mound from 3 to 4 feet high1 covers the south face, hiding the foot of the wall, which is not protected by a ditch. The dry sandy bed of a river runs along this fo.ce, and also along a part of the northern face.

There are five gateways in the line of works, which are flanked by masonry towers of more substantial construction than the others.

On an artificial rising ground in the town, rather towards the eastern face, is the Thakoor's Castle, forming a keep to the place. It is of a square form1 each side being about 80 yards long. It consists of a number of buildings, sur­rounded by a masonry wall flanked by towers, in the same manner as the walls of the town, and higher than the buildiugs about it ; but it is not wholly isolated from them.

The fort of Ahwah is much hidden by trees, which surround it on all sides except the south. They stand in thick clusters, lining the defences both inside and out, covering the exterior, and rendering all examination at any distance outside a matter of great difficulty. The contour of the place is thus almost completely concealed.

The preceding information was only obtained after the evacuation of the fort by the enemy. There was no plan, except two native ones, on which but small reliance could be phl.ced, and no information of any sort could be obtained con­cerning the works of any one face. The garrison was understood to consist of about 1,500 men, and they had about 25 guns of small calibre, throwing shot weighing from 6 to 2 pounds.

SIEGE OPERATIONs.-The field force, under the command of Lieutenant Colonel Holmes, effected a junction before the place on the morning of the 19th January, 1858. It was composed as follows:-

Her Majesty's 9-,th Regiment .. 300 Jlth Company Royal Engineers 110 Ditto 83rd 140 Bombay Artillery . · 11 0

12th Native Infantry. 140 Native Regular Cavalry ...... 200 10th Ditto 320 Scinde Horse ........ ... ..... 500

Total .... . 900 Grand Total ...... 1820 Immediately on an·ival before the place a reconnaisance was made. The

investment had been ma.de by the cavalry two or three days previously, and it was now rendered more complete.

On account of the trees, the walls could onlv be seen here and there at isolated points, except on the south, where thej were fully open to view. It was necessary therefore to reconnoitre in places to within 400 yards, by which enough was seen to recommend the south as the front to be attacked. It should also be mentioned that the ground in front of the south face was very favourable for the construction of batteries and approaches; at the same time it was not forgotten that with regard to the other faces, the trees would afford good cover to an at.tacking force. Accordingly camp was pitched to the south, at a distance of 2i000 yards from the town.

First Night, January 19th, 1858. A half sunken battery for 3 howitzers and 1 mortar, 1 magazine, 1 traverse, and 1 epaulment, (No. 1 in Plan''"), was

• It has not been considered necessary to lithograph this sketch.-Eo.

ON THE OPERATIONS AT THE SIEGE OF ABWAH. 43

trnced and executed this night. A portion of a hillock was cut away to form No. II Battery for two mortars and one magazine. ·

Their special object was to maintain a fire of shells on the town next day, which, being directed from several points at the same time, would force the enemy to abandon the fort and fall into the hands of the investing force. No. 1 Battery was also intended to enfilade the south face, with a view to further operations, but as it had become dark when its site was fixed upon, the correct­ness of it.s position could not be· ascertained ; yet as it was thought best to execute it that night (the 19th inst.), and thus avoid delay, a position favourable for execution was chosen, though for purposes of enfilade it should have bcC'n more to the right.

Batteries Nos. I and II wero completed and armed before noon on the 20th inst.; they commenced firing at noon, in conjunction with Captain Aitkin\, field battery of four 9-pdrs. and two 12-pdr. howitzers, which had taken a forward position on the left near the spot marked A in the sketch which accom­panies thi~ report.

This fire continued for two or three hours, the enemy replying at intenal<J , but not showing any intention to leave the fort. A closer examination of the south face and of the ground in its front was therefore made; the point bin the wall near the South-east Bastion was selected for the position of a breach, and a fo.:vourable rise in the ground was observed on which to construct a breaching battery.

In ·the afternoon of the 20th, a house c, in front of the eastern gate, whirh was occupied by the enemy, and to which they had run out a. gun (afterwards withdrawn), was taken and blown up with gunpowder.

Estimate of Men, Tools, and ~Ia.terials.-lst Relief.

No. 1 Battery. No. 2 Battery. Guard of the Trenches. . 50 men ............• , 50 ,vorkingparty ........ 106 ,, ...••••••.• 10 Sappers . . . . . . . . .. .. . 18 . . . . . . . . • . . • .. 7

174

No. 1 Battery. Picks........... 47 Sho\'els.............. 59 Hammers ... . Mallets .......... . ~Icasurin g Rods .. Do. Tapes (S0yds. each) LeYels ............. .

4 2 6 4

No. 2 Battery. 7

11

2

67 Total.. 241 men

Total. 54 Picks. 70 ShoYt:!ls. 4 Rammcrs. 2 Mallets. 8 Measuring Rods. 4 ditto Tapes. 1 Le,·el.

Lanterns . . . . . . . . . . . . 1 Lantern. Trncing Pickets . . . . . . 2,5 10 35 Tracing Pickets. Sand-bags ............ 1,390 ,, ... 1,390 Sand-bags. :Mining Frames . . . . . . 3 . . 2 5 Mining Frames. Sheeting Planks ... , . . 3 3 6 Sheeting Planks,

Second Relief-Men, tools, and materials as before for the fu-st half of this relief.

I •

44 ON TIIE OPERATIONS AT TIIE SIEGE OF AJIWAII.

Third Relief:-

Rrpah~in~ Embrasm·es . ..... , . , , . • • • •, 8 Sappers. ) Total- 16 Sappers. Demolishing House . . . . . . . . . . . . . . . . . . S ,,

4 Picks. 4 Shovels. 1 1\foasuring rod.

SO lbs. powder.

Tools and Materials for ditto.

12 ft. hose. 9 in. port.fire.

11 ft. slow match.

2ncl night, January 20t,h.-Battery No. II was traced ancl executed: it wa.~ macle half sunken for 6 gw1s ,-rith a magazine and a traverse. 300 yards of trc·nch communication in rear were also trnced and executed so as to afford :-.ufficient cover ; this was rendered necessary as the ground in rear ·was open and the road on the 1·ight wa.s enfiladed Ji·om a mowid (/) jutting ont from the bOuth-east bastion.

Riflemen were placed in ad,·anced positions on the rig:ht and left. Battery No. II was abandoned, and its mortars moved further forwa.r~

obtaining coyer under a bank, which thus formed Battery No. IV. Battery No. III could have opened fire with the siege ordnance, either dw·ing

1he 21st inst. or at daylight on the 22nd, after which it was cousideredprobablc­that a few how·s wollld have sufficed for the ta.king of the fort i but at this time information was received that a double line of works existed all arow1d the fort, excepting for about 200 or 300 yards on the eastern face where there wa.;; only a single line.

'!'his information came from a nath-e; it was given first in camp, and aftel'~ wards in view of the place, at both times in the hearing of two or three officers well acquainted with the language of the com1try. The native also pointed out the eastern gate and described its approaches and the ground within.•

The e\'idence of this native, though appearing correct, as guns had been fu·ed se,·era.l times from the south front frnm points not immedfately on its face, would not have been considered sufficient to change the plan of the attack had it not coincided with two nathc plans which had come into our hands from different SOlU'CCS.

On account of this informatfon, an examination of the east face ( occupJ;ng from two to three hours) was made on the afternoon of the 21stinst., after which i t was decided to erect a battery on a convenient rising grmmd, which might ist:rn either to breach the works at a point ( e) near the centre of the ea.steru. front, or open a passage tlu-ough the eastern gate.

The ground more to the right of this position was not so favourable for thu­construction of a battery, nor was the view of the wall so clear.

It was necessary fhst to burn the brushwood, which concealed the foot of thc­wnJl of this front: this was intended to be done by means of carcasses or fire­ball,.

B,ttteries I , III, and IV were firing at inten·als to silence the guns of the: fort and enfilade the sonth and east faces.

• This afterwards proved to be correct.

ON THE OPERATIONS AT TIIE SIEGE OF ATIWAH. 4.j

Estimate of Men, Tools, and Mate-rials. Gunrd of the trenches . . . . . . . . . . . . . . . . . 100 J ~:;~::g. ~-a~~~-_· .... : : : .'::::::: .... :::::: li~ Total-308 men.

Tools in proportion.

{ Snncl-bags . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3,000.

Materials . . :Mining frame& .. . . . . . . . . . . . . . . . . . . . . . . . . 3. Sheeting planks . . . . . . . . . . . . . . . . . . . . . . . . . 3.

There was no working party in the trenches after 9 A.M., on the 21st, 011

nrcount of the heat. On the 3rd night (21st January),Battery No. V, for breaching, was traced for

4 !,runs. A magazine was provided for it, but no traverse. This battery was made half sunken, and was partially executed on this night.

1-10 yards of trench communication in rear we1-e also traced and commenced, and positions for riflemen were taken up on the mow1d, some low ruins on it~ 1·ig-ht, and behind some trees.

Battery No. V could not be armed this night as it was found necessary to approximate its form to that of an elevated battery to give it a better command. Independently of this it was also considered advisable to withdraw the ,vorking parties of the European regiments (who alone were good for trench work) during the heat of the sun, as the troops had been very hard-worked.

Batteries I, III, and IV fired occasionally.

Estimate of Men, Tools, and Materials. No. III Battery. No. V Battery.

Gunrd of the trenches . . . . 30 . . . . . . . . . . . . • . 40 Working party . . . . •. . • . • 30 ........•..... 100 Sappers . . . . . . . . • . . . . • . . 8 . • • • • • • • • • . • • • 20

68 160-Total, 228 men,

Tools in proportion. Materials. Total.

Sand-bags... . • . . 350 1,750 2,100 Sand-bags. Mining Frames.... 3 3 Mining Frames. Sheeting Planks.. . 26 26 Sheeting Plnnks.

4th night, 22nd January.-The Breaching Battery No. V was completed nnd armecl this night, and the communication in rear was completed so as to afford a sufficient cover. Carcasses and light balls were thrown into the brushwood in front of the gate, but without success. As it was considered a point of some importance that this brushwood should be cleared away, it was decided to rnll a sap-roller, or gabion filled with combustibles, up to it on the following 11ight, and to provide other means besides for burning it by hand. All arrange­ments could in the mean time be made for the assault, which would take place un the following day after the guns (which would open fire at daybreak), had made a practicable breach.

Battery No. III fired occasionally to enfilade the east face. Battery No. II •belled the Thakoor's house and ,icinity, and No. I enfiladed the south face. The

4G ON 'IIIE OPERATIONS AT TllE SIEGE OF AlIW.1.H,

"hole were nlso to silence nny gun that might fire from the fort. The European infantry were removecl from the batteries from O A.)!, to 5 r.M. on the 23rd J:111uary.

Estimate of Men, Tools, and Materials. On the Right. On the Left.

Guard of the trenches . .. .. • 40 30 Working party ........... , 77 .. .. • .. • • .. • .. 33 Sappers ................. , 14 . . .. . . . .. . .. 9

131 72-Total, 203 men.

There wns no second or third relief, the first relief remaining in position till 9 .\.M. on the 23rd inst.

J th night, 23rd January.-The guns were removed from No. III Battery. Preparations were made this night, in rear of Battery No. V, to burn the

brushwood above-mentioned. The night Vi'US stormy an<l dark in the extreme, with thunder and a deluge of min. Under the superintendence of an officer of Engineers two non-commissioned officers of that corps (Sergeant Doherty and Corporal Kerr), went forward and inspected the position of the brushwood to tirlect the best point for burning it. It was reported as useless to attempt it on that night, much of it being too supple to burn easily e,'ell had there been no 1·ain. The attempt was considered not worth the risk of the lives of the men engaged: the party sent forward to examine were fired upon, and it was decided that the breaching battery should open on the gateway at daylight with :-.hot and shell to clear a passage. Before daylight riflemen filled the ground in front, and every arrangement was made for the assault, parties being detailed with materials for blasting, gabions for lodgments aml fascines for ditches, a11d also some with scaling laddt:rs and others with sledge hammers, axes, &c.

It was found however in the morning that the intense darkness of the night har1 enabled the enemy to escape from the fort, which was therefore occupied by the besieging force at about 6 A.M. on the 24th inst.

Estimate of Men, Tools, and Materials. On the Right. On the Left.

Guard of the trenches .• .. .. 100 ................ .. "Vorking party. . . . . . . . . . . . 6 • • • • . . • • . • . . . . . • . • • . • • • • ,,

1 Hand-saw. 2 Bill-hooks.

Tools.

1 Felling axe. I Dark Ian tern.

Return of Men, Tools, nod ifoterials used at the Siege. Tools.

Picks.............. 80 Sho,·els ............ 104 J:nmmers 4 )lallets . . . 4 Tapes .. .. . .. . . 7 J,evels 2 Bill-hooks . . . . . 25

Lanterns.......... 5 Measuring rods • • • • 8 Clnsp kniYes . • • ~9 Fascine chokers. I Tracing pickets . ~ [jQO

Hand-saws ....... • Felling u:ices

ON TllE OPERATIONS AT TIIE SIEGE OF AHWAII,

Materials. Sand-bags ....... . . l\Iining frames .. . Sheeting pieces .

Men.

6,490 II 26

Guard of the trenches (gencmlly at two reliefs) . . . • . • . • . . . . 100 Working parties ditto . • .. . . . . . . • • 350 Camp duties, gunrds, pic:quets, sick, &c........ • • • • . • . • . . . • 450

Total Infantry. . . . . . • • • • . • . . • • • • • • • . . • • • • • . • • 900 Engineers...... . • • . • . • • . • • • • • . • • • • • • • • • • . • • . 110 Artillery . . . . . • . . • . . . . • . . • • . • . . . . . . . • • • • • • • . • 110

Cavalry { Nati,·e Regular • • . . . . • • • . . . • • 200 j 700 Ditto Scinde Horse... • • • • . . . • 500 • • " • • • •

Grand Total. . . . • • . • . . • • . . . • . • . • . . . . • • • • • • • .. 1,820

Return of Ordnance employed at the Siege, and Ammunition expended.

{ 7

No. of Pieces. No. of rounds expcnd~d. 2 18-pdr. guns . . . . . . • • . . • • . . . . • • • . • • . . . . . • • • • • • • 2'1 2 8-in. howitzers • . . • . • • • . . • . . . . . • • • • • . . . . . . . . . 168 2 24-pdr. howitzers ..••.•.•.•....•.•.••...•...... 118 2 12-pdr. howitzel's...... • . • • • • • . • • . . . . .. .. • . . • . • 32 4 9-pdr. guns ...... . ..•...•........•••.•••••.. 313 2 8-in. mortars ..••......•••••••••••.. . •..•..•..• 301 2 5½-in. ditto ......• _. • . . . . . . • . • . . . . . . . • • • 308 For demolition of houses, &c.. • • • • 80 lbs. of gunpowder. Total Ordnance employed . . . . . . . • 16 pieces.

Batteries N os. I, III, and V were constructed of sand-bags, the greater part of which were afterwards recovtlred.

The following Officers of Engineers were employed at this siege:­

Lieutenant A. Davidson, Bombay Engineers. D. C. ,v alker, Royal Engineers. J. B. Paterson, Royal Engineers.

The Commanding Engineer of the Rnjpootana Field Force, (Major Trcmcn~ heere, Bombay Engineers),joined the force before Ahwah on the 23rd January, but permitted me to remain in command of the Engineers until the place fell.

(Signed)

I have, &c., C. E. CUMBERLAND, Royal Engineers,

Com. Engineer at the Siege.

I I.

48

PAPER IX.

REPORTS ON THE ENGINEERING OPERATIONS DURING THE

DEFENCE OF LUCKNOW, IN 1857.

EXTRACT FROM THE REPORT OF MAJ. GEN. SIR JOHN INGUS, K.C.B., ON THE DEFENCE OF THE RESIDENCY AT LUCKNOW, DATED SEPT. 26, 1857.

u The description of our position and the state of our defences when the siege b('gan" are so fully set forth in the accompanying memorandum furnished by the Garrison Engineer that I shall content myself with bringing to the notice of his Lordship in Council the fact that when the blockade was commenced only two of oux batteries were completed, part of the defences were yet in an unfinished condition, and the buildings in the immediate vicinity, which gave coYer to the enemy, were only very IJartially cleared away. Indeed, ow· heaviest losses have been caused by the fire from the enemy's sharpshooters, stationed in the adjoining mosques and houses of the native nobility, the necessity of de­stroying which had been repeatcclly drawn to the attention of Sir H. Lawrence by the staff of Engineers; but his invariable reply was, "Spare the holy places, and private property too, as far as possible;" and we have consequently sufferecl severely from om· very tenderness to the religious prejudices, and respect to th1c1

rights of our rebellious citizens and soldiery. As soon as the enemy had thoroughly completed the investment of the Residency they occupied these houses, some of which were within easy pistol shot of our barricades, in immense force, ancl rapidly made loo1Jholes on those sides which bore on om· post, from which they kept up a terrific and incessant fire day and night, which caused many daily casualties, as there could not have been less than 8,000 men fuing at one time into om· position. Moreover, there was no place in the whole of our works that could be considered safe, for several of the sick and wounded who were lying in the banqueting-hall, which had been turned into a hospital, were killecl in the very centre of the building, and the widow of Lieutenant Dorin, and other women and children, were shot dead in rooms into which it had not been previously deemed possible that a bullet could penetrate. Neither were the enemy idle in erecting batteries. 'l'hey soon had from 20 to 25 guns in 1msition, some of them of very large calibre. These were planted all round our 11ost at small distances, some beiag actually ,•rithin 50 yards of our defences, but

• The garrison was concentrated at the Residency, on the 1st July, 1557, afler blowing up the Muchee Bowun.

ON TllE DEFENCE OF TIIE RESIDENCY AT LUCKNOW. 49

in places where our own heavy guns could not reply to them; while the persc .. vernnce and ingenuity of the enemy in erecting barricades in front of and around their guns in a very short time rendered all attemps to silence them by musketry entirely unavailing. Neither could they be effectually silenced by shells, by reason of their extreme proximity to our position, and because, moreover, the enemy had rccow·se to digging very narrow trenches about eight feet in depth in rear of each gun, in which the men lay while our shells were flying, and which so effectually concealed them, even while working the gun, that our baffled sharpshooters could only see their hands while in the act of loadllig.

The enemy contented themselves with keeping up this incessant fire of cannon and musketry until the 20th of July, on which day, at 10 a.m., they assembled• in very great force all around our position, and exploded a heavy mine inside our outer line of defence at the ,v ater Gate, The mine, howe,·er, which was close to the Redan, and apparently sprung with the intention of destroying that battery, did no harm. But as soon as the smoke had cleared away the enemy boldly advanced under cover of a tremendous fire of cannon and musketry, with the object of storming the Redan. But they were received with such a heavy fire that after a short struggle they fell back with much loss. A strong column advanced at the same tin1e to attack Iunes's post, and came on to within 10 yanls of the palisades, affording to Lieutenant Loughnan, 13th Native Infantry, who commanded the position, and his brave garrison, composed of gentlemen of the uncovenantedservice, a few of Her 1'-iajesty's 32nd Foot, and of the 13th Native Infantry, an opportunity of distinguishing themselves, which they were not slow to avail themselves of, and the enemy ,vere driven back with great slaughter. The insurgents made minor attacks at almost every outpost, but were inva.riably defeated, and at 2 p.m. they ceased their attempts to storm the place, although their muskeh-y fire and cannonading continued to harass us unceasingly as usual. Matters proceeded in this manner until the 10th August, when the enemy made another assault, having previously sprung a mine close to the Brigade mess, which entirely destroyed our defences for the space of 20 feet, and blew in a great portion of the outside wall of the house occupied by ~fr. Schilling's garrison. On the dust clearing away a breach appeared, through which a regiment could have advanced in perfect order, and a few of the enemy came on with the utmost determiation, b1J.t were met with such a withcring flank fire of musketry from the officers and men holding the top of the Brigade mess that they beat a speedy retreat, leaving the more adventurous of their number lying on the crest of the breach. ,vhile the operation was going on another large body advanced on the Cawnpore Battery, and succeeded in locating themselYcs for a few minutes in the ditch. They were, however, dislodged by hand grenades. At Captain Anderson's post they also came boldly forward with scaling ladders, which they planted against the wall; but here, as elsewhere, they were met with the most indomitable resolution, and the leaders being slain, the rest fled, learing the ladders, and retreated to their batteries and loopholed defences, whence they kept up for the rest of the day nu unusually heavy cannonade and musketry fire. On the 18th of August, tho enemy sprang another mine in front of the Sikh lines with very fatal effect.

• Sec the Plan at the end of the next Paper, G

50 ON THE DEFENCE OF THE RESIDENCY AT LUCKNOW.

Ca1)tain Orr (unattached), Lieutenants Meecham_ and Soppitt, who_ commnn~ed the small body of drummers com1)osing the gnrnson, were blown mto the all' ; but providentially retlu-ucd to em·th with no fw·thcr fojury than a se,·erc shaki~g. 'l'he garrison, howeYer, were not so fortunate. No less than 11 men were buned alive nnder the ruins, whence it was impossible to extricate them owing to the tremendous fu·e kept up by the enemy from houses situated not ten yards in front of the breach. The explosion was followed by a general assault of a less determined natw·e than the two former efforts, and the enemy were conse­quently repulsed without much difficulty. But they succeeded, under coYer of the breach, in establishing themselves in one of the houses in our position, from which they were cl.riven in the evening by the bayonets of Her Majesty's 32nd and 84th Foot. On the 6th of September the enemy made their last serious assault. Having exploded a large mine a few feet short of the bastion of the 18-pdr. gun in ~Iajor Apthorp's post, they adYanced with large heavy scaling ladders, which they planted against the wall, and mounted, thereby gaining for an instant the embrasure of a gun. They were, however, speedily driven back with loss by hand grenades and musketry. A few minutes subsequently they sprang another mine close to the Brigade mess and advanced boldly; but soon the corpses strewn in the gnrden in front of the post bore testimony to the fatal accuracy of the rifle and musketry fire of the gallant members of that garrison, and the enemy fled ignominiously, leaving their leader-a fine-looking old nati,·e officer-among the slain. At other posts they made similar attacks, but with less resolution, and everyw·here with the same want of success. Their loss upon this day must have been very heavy, as they came on with much determination, and at night they were seen bearing large numbers of theil' killed and woundL·d over the bridges in the direction of the cantonments. The above is a faint attempt at a description of the four great struggles which have occurred during this protracted season of exertion, exposure, and suffering. His Lordship in Council will perceive that the enemy im·ariably commenced his attacks by the explosion of a mine, a species of offensive warfare for the exercise of which our position was unfortunately peculiarly situated, and had it not been for the most untiring vigilance on our part in watching and blowing up their mines before they were completed, the assaults would probably have been much more numerous, and might, perhaps, have ended in the capture of the place. But by countermining- in all directions we succeeded in detecting and destroying no less than four of the enemy's subtcrraneous advances towards important positions, two of which operations were eminently successful, as on one occasion not l~ss than 80 of them were blown into the air, and 20 suffered a similar fate on the second explosion. The labour, however, which devolved upon us in making these countermines in the absence of a body of skilled miners was very heavy.

The Rig-bt Hon. the Governor General in Council will feel that it wo11ld be impossible to crowd within the limits of a despatch even the principal eYEnts, much more the individual acts of gallantry which have marked this protracted struggle. But I can conscientiously declare my conviction that few troops have ever undergone greater hardships, exposed as they have been to a never-ceasing musketry fire and cannonade. They have also experienced the alternate Yicis~ situdes of extreme wet and of intense heat, and that too with very insufficient

ON TllE DEFENCE OF TllE RESIDENCY AT LUCKNOW, 51

~helter from either, and in many places without any shelter at all. In addition t,i having had to repel real attacks, they have been exposed night and day to the hardly less harassing false alarms which the enemy have been constantly l.lising. The insurgents have frequently fired very heavily, sounded the advance, !rnd shouted for several hours together, though not a man could be seen, with the Yiew, of course, of harassing our small and exhausted force, in which object they succeeded, for no part has been strong enough to allow of a portion only of the garrison being prepared in the eYent of a false attack being turned into a real one; all, therefore, had to stand to their arms, and to remain at their posts until the demonstration had ceased; and such attacks were of almost nightly orrurrcnce. The whole of the officers and men have been on duty night and day ,luring the 87 days which the siege had lasted up to the arrival of Sir James Outl'am, G.C.B. In addition to this incessant military duty the force has been nightly employed in repairing defences, in moving guns, in burying dead :1nim1ls, in conveying ammunition and commissariat stores from one place to another, and in other fatigue duties too numerous and too trivial to enull..lerate here. I feel, however, that any words of mine will fail to convey any adequate iden. of what our fatigue and labours have been-labours in which all ranks and classes, civilians, officers, and soldiers, have all borne an equally noble part. -All have together descended into the mine, and have together handled the shovel for the interment of the putrid bullocks, and all, accoutred with musket and bayonet, have relieved each other on sentry without regard to the distinctions of r,1nk, civil or military. Notwithstanding all these hardships, the garrison has made no less than five sorties, in which they spiked two of the enemy's heaTiest guns, ancl blew up several of the houses from which they had kept up their most harassing fire. Owing to the extreme paucity of our numbers, each man was taught to feel that on his own individual efforts alone depended in no small measure the safety of the entire position. 'l'his consciousness incited every officer, soldier, and man to defend the post assigned to him with such desperate tenacity, and to fight for the lives which Providence had entrusted to bis care with such dauntless determination, that the enemyi despite their constant attacks, their hcnYy mines, their oYerwhelming numbers, and their incessant fire, could ne,·er succeed in gaining one single inch of gl'ound within the bounds of this straggling position, which was so feebly fortified that hnd they once obtained a footing in any of the outposts the whole place must ine\"itably have fa\1cn.

If further proof be wanting of the desperate nature of the struggle which we ho.Te, under God's blessing, so long nnd so successfully waged, I would point to the roofless and mined houses, to the crumbled walls, to the exploded mines, to the open breaches, to the shattered and disabled guns and defences, and, lastly, to the long aud melo.ncholy list of the brave and deYoted officers and men who have fallen. These !=.ilent witnesses bear sad and solemn testimony to the way in which this thblc po;.;ition has been dcfenclecl. Dul'ing the early part of these Yicie:situdes we ,..-C'1·c left without any information whatever regarding the posture of affa.irs outsir1e. An occasional spy did indeed_ cam~ in with ~he object of inclueing our Sepoys and servants to deserti but the mtelhgencedenved from 5uch sources was, of' coul'se, entirely untrustworthy. ,ve sent our messengers,

({! ON TUE DEFENCE OF THE RESIDENCY AT LUCK.NOW.

daily calling for nid nnd asking for information, none of whom ever rctu~cd until the 26th dny of the siege, when a pensioner named Ungud came back with a Jetter from General lfayclock's camp, informing us that they were ndl'nncing with a force sufficient to bear down all opposition, and would be with us in five or six days. A messenger was immediately despatched, requesting that on the e¥enin o- of their arrival 011 the outskirts of tho city two rockets might be sent up, in orde~· that we might take the necessary measures for assisting them while forcing their way in. The sixth day, however, expired, and they came not; but for many eve11ings after officers and men watched for the ascension of the e:1pected rockets, with hopes such as make the befll•t sick. We know not then, nor did we learn until the 29th of August (or 35 days later), that the relieving force, after having fought most nobly to effect our delivemnce, bad been obliged t o fall back for reinforcem~nts; and this was the last communication we received until two days before the arrival of Sir James Outram, on the 25th of September."

REPORT ON THE DEFENCES OF THE RESIDENCY AT LUCKNOW,

BY LIEUT. J. c. ANDERSON, M.E.

Lucknow, October 5, 1857. The outbreak at Meerut and Delhi, and reports of general disaffection among

the Sepoys, caused Sir Henry Lawrence to take immediate measures for the defence of this place. Some time previously he had selected the Muchee Bowun as a site for our magazine nnd stores, and on account of its very commanding position and the moml effect that the occupation of it would exercise over the city, he in the first instance proceeded to strengthen it. The works were com­menced on the 17th May, and carried forward with unremitting energy by Lieut. Innes, under the general direction of l\Iajor Anderson, Chief Engineer, until the commencement of the siege.

The defence of the Residency was also commenced, though at first it received a secondary share of attention. It was not till after the mutiny in cantonments (30th l\Jay), and the subsequent mutinies of corps in the district, that it became apparent that we should have probably to defend ourselves against a combined uttack of mutineers and rebels from the count1y and city. The more clear this Uecamo, the more clearly the inadequacy of the l\luchee Bowun as a fortified position became apparent. It was also seen that, if the mutineers came on in great force, we had not sufficient hands to man both it and the Residency; and having ascertained, after full consideration, the defects of the Muchee Bowun, both as regards defensive measures and shelter of troops, and the large European community, Sir Henry Lawrence made up his mind to abandon it on the investment of the city by the enemy.

On this being decided (11th June), the defences of the Residency were pro­ceeded with with vigour. Prior to this, the Chief Engineer was doubtful as to the extent of the force he had to shelter within the line of defences, or to man the works; but now he could form a definite plan, and he lost no time in forming a connected line of defensive works round the buildings he thought it necessary to occupy.

The Residency Compound was first protected by a line of parapet and ditch across it; a strong battery, since named II the Redant was constructed in a. co11icr of the ga1·den, which furnished a commancl over the iron bridge.

ON TilE DEFENCE OF THE RESIDENCY AT LUCl<NOW. 53

A bn~t~ry (called_" the Cnwnpore 11) was constructed at the opposite point of our ~os1tion enfilading the Cnwnporc Road, and was then deeigned chiefly as n barrier to the approa~h of mutineers from Cnwnporc.

'l'wo other batteries were partially constructed, one between Gubbins's and Ommn~mcy'a Compounds, the other between the slaughter-house and sheep-pen; but neither were ready at the commencement of the siege, and ,vant of labour prevcn ted their being completed afterwards.

Heavy and light guns and mortnrs, more or less protected by parapets, were placed in various positions intermediate to the above-mentioned principal batteries. 'l'hose positions are marked in the annexed sketch, though of course ,•n.rious changes occurred during the siege; a gun or mortar having been fre• quently required to silence an enemy's battery and withdrawn when the object was accomplished.

~Ir. Gubbins, by means of labourers procured by his subordinates, canied on the defences of his own compound; and the general line round our position was continued from battery to battery, and house to house, by abattis (in lanes), aud by parapets and ditches, or stockades.

Outside our line of works also a great amount of labour was required. Masses of buildings extended to within a fe·w feet of us in nearly every direction , aml though some of them would net as traverses to us from the enemy's batteries. the majority were a most undoubted source of annoyance to us, aml it was necessary to proceed with their removal as vigorously as our means permitted. Se,·cral mosques, which occupied positions commanding us, were left alone, much to our future injury; but I belie,•e the nason that prevented their removal was a good one, namely, the danger of precipitating an outbreak before we were prepared for it. But, apart from this, the demolition of private buildings was far from complete. The affair of Chinhut brought the enemy upon us earlier, I believe, than was anticipated by any individual of our force, ancl our command of labow· ha,·i.ng been limited, we had to close our gates with nothing in many places separating us from the besiegers but the width of the streets. The hou<.:.rs that remained became nests of rebels, and besides forming secure starting points for their mines, enabled them fl'Om under shelter to keep up a dc:.ully fire of musketry upon us day and night, and it is to it, and not to round shot, that we have to attribute the greater part of ow· casualties. The latter was main]y injuriou:i in destroying the buildings occupied by our troops and camp followers; nnd, though the loss of life, considering the amount of battering they sustained, was much less than was to be expected, it was o. con$tant souTce of danger and annoyance to the garrison, and the repair of damage entailed hcrwy laboul' on men ,vho were weakened by exposure and want of rest.

The enemy proceeded to invest the IJlace immediately on the rehu·n of our force from Chinhut on the 30th June. The )1uchee Bowun was still garrisoned by our troops, though the treasuTC and greater portion of the munitions ancl stores had been previously removed to the Residency, and it now became an object of primary importance to withdraw the garrison without loss. A tck­grnphic message was communicated to Lieutenant Innes, the Engineer Officer, to the effect that the powder in the magazine, about 200 barrels1 was to be used in blowing up the fort, and that the gan-ison wns to leave at miclnight on the ht July. This order was carried out with perfect success, and the garrison marched into our gates without the loss of a man,

,j,1 ON TBE DEF.E.NCE OF THE RESIOENCY AT LUCI\NO'\Y,

The Gurclcn Buttery was one of the',irst cstablishecl by the enemy. It player! on the Guard House ~t the Cnwnpore Battery, the Battery itself, Hrigaclc Mei-s, Anderson's, and Judicial Commisijioncr's. 'l'he combined fire of heayy guns nnd musketry on the Cawnpore Buttery became so deadly that our guns could not he served and cventu11lly it was thou...,.ht necessary to withdraw them and to leave the ~osition to be cl~fendccl by m;sketry, and to repair the po.1·apcts as fast as they were damaged by the enemy's round shot.

At the beginning of the siege, the 8 inch howitzer which fell into t~e enemy's hands at Chinhut1 was placed out of sight of our guns on the oppoente bank of the river near the bridge of toats, and kept up a destructive fire on the ~csi­dcncy. It was by one of the shells from it that Sir Henry Lawrence was killed.

Batteries were also established by the enemy on the 1·ond leading from the iron bridge, in front of Gubbins's House, the Brigade ~less, and Post Office, and at the Clock Tower, and all the buildings were more or less damaged Ly them. A portion of the Residency was battered down, and six men were buried in the ruins. l\Iany of the buildings were reduced to such a state as to appear to be quite untenable, but the garrison continued to occupy nearly all; and though the defences of the posts have been very much weakened by the continued and heavy fire, not a sing:le one has been abandoned; on the contrary, several buildings (Financial Commissioner's, S,1go's, and Innes's) haYc been occu11ied and strengthened since the commencement of the siege.

" ' hen the enemy found that neither by repeated attacks, nor the destruction of our buildings, he could force us from our posts, he had recourse to mining. This had been anticipated, but the chief engineer, acting under the suggestion of the late Captain Fulton, would not take the initiative, as he apprehended that our enemies would at once follow our example, and that the unlimited commancl of labour they possessed would give us a poor chance of competing with them.

The first mine exploded by the enemy was at the Reclan l20th July). It 11rcceded a general attack, and both as regards direction and di!:>tance was a complete failure. This was followed by one at the angle of the Scikh Square, and is the only one from which any loss of life on om· side has been sustained. The sound of the mining had not been heard owing to the proximity of the caYalry horses, and the guard were completely surprised (27th J ul,r). Scyen drummers were killed on this occasion.

1',o other mines1 at the building occupied by the :Martiniere boys and at Sago's1 were also exploded (10th August), but beyond breaking the outer line of walls, did no damage. The enemy in no case showed any great alacrity in assaulting the breaches, and we soon formed retrenchments in rear of thorn.

,ve had, meanwhile, commenced countermiuing, and on the 5th August foiled a. mine of the enemy's against the Guard House at the Cawu1Jore Battery, and since then, up to the arrival of the relieving force, we luwe been incessantly employed in mining and countermining. \Ve have generally worked into their galleries, and after having frightened the miners away, ha,·e destroyed them1 or, in some cases, we have blown in their gallerie; Ly charging and firing our own. I need hardly add ttat this was a service of danger.

'l'wo of our mines, for directly offensive objects, require separate notice: the one at Sago's, to the enemy's guaa.'d-room, which we blew down with a loss to them of, it is supposed, between twenty and thirty men: the sccond, to Johannc1-J' l~ouse, in which w~ dcstroycd aboye eighty of the cnemr, This explosion was followed by a isorhe to coyer the demolition of the remainder of the house uml

ON TltE DtFEl<Cll OF THE RESIDENCY AT LUCKNOW, 55

one adjoining, which object was effectually nccom1Jlished, nnd relieved us from the clestructi,·e fire of many of the enemy's best marksmen. I may mention that scYeral sorties were made on other occasions, and with equal success.

"re had, on the arrival of the relieving force, fifteen galleries ready for coun­tcnnining further operations of the enemy. Several of the enemy's galleries have since been discovered and destroyed.

I believe I have now noted every measure of importance -with reference to the d(•fencc and attack of the place in an engineering point of view, and it remains for me to state the means at our disposal for carrying on work.

During the early part of the siege we had working parties of Her Majesty's 32nd Regiment. On one work, du.ring the night, I have had forty.two men. The soldiers, however, ha.d their other duties to perform, they were exposed to rain, and were very often under arms, which prevented their having a proper amount of rest. They could therefore have little physical strength left to work in the trenches, and as the siege progressed their numerical strength became so much reduced that it was necessary to give up European working parties almost entirely, and to depend on the Sepoys. The latter came forward most willingly, and I cannot speak too highly of the way in which they worked. They haYe also been of material assistance in our mining operations, and a party of the 13th Nath-e Infantry-thanks to the good management of Lieutenant Aitken­have constructed a battery for an 18·poundcr, worked the gun, and dug a shaft and ga.llery at their own post.

There has been but one squad of European miners (eight men under Sergeant Day}, all of whom have worked with the most unremitting zeal throughout.

As regards general su11erintcndcnce, the late 1'ilajor Anderson, Chief Engineer, designed the defences of the l\Iuchee Bowun and Residency, and until shortly before his death, directed the construction of the ,arious works and repairs.

Captain Fulton became the Senior Engineer Officer on the demise of Major Anderson on the 11th August. He had constructed the greater portion of the defences, powder magazines, &c., and up to the day of his death displayed the most unremitting energy, in spite of bad health, in advancing our work. In particular he took a most active part in foiling the enemy's attempt to destroy our adYanced post by mines, and the manner in which he conducted the blasting operations during our sorties, invariably excited the admiration of all who were present, officers and men.

In the performance of the above-mentioned, and engineering operations generally, he received the most able and untiring support from Lieutcnauts Hutchinson, Innes, and Tulloh, and the late Lieutenant Birch, and latterly, since Captain Fulton's death, I have received much assistance from Lieutenant Hay, Assistant Field Engineer. 'l'hc active part I myself have taken in the superintendence of works, has been small, owing to my having suffered from continued ill health.

Finally, I beg to bring to the notice of the Brigadier the excellent service performed by the late Mr. Casey, head accountant to the Chief Engineer, who had been Sergeant l\Iojor of :Sappers, and who was recommended by Major Anderson for the rank of Assistant Field Engineer; of the late Mr. Supenisor Barrett; Mr. Beale, Overseer; and Sergeant Ryder, Assistant Overseer-all of whom have left families behind them,

J. C. ANDERSON, Lieutenant, Garrison Engineer.

''

I I,

I

l I

EXTRACT FJlOM A REPORT DY MAJOR GENERAL SIR JAMES OUTRAM, G.C.B., ON THE DEFENCE 0}" LUCKNOW Al"TER THE RELIEF OF THE RESIDENCY•

Camp, Alum Bagh, November 25, 1857, SIR,

I have the honour to acquaint His Excellency the Commander-in-Chief with the proceedings of this force since the 28th of September, the date of 1:1Y last despatch, and b2g to refer to the documents enumerated in the margin. General li(n-elock has commanded the field force occupying the palaces and outposts, and Brigadier Inglis has continued in command of the Lucknow gar­rison-an arrangement that has proved most convenient.

The first work required was to open a. roadway through the palaces for the heavy train, which had been brought into one of the gardens on the 27th Sep­tember, and by the 1st October was safely parked within the entrenchment.

Contrary to the expectations expressed in my last despatch, the enemy, relying on the strong position of their remaining battery (the one known as II Phillips' Battery), continued to annoy the garrison by its fire, and to maintain there a strong force. Its capture, therefore, became nece~sary, and this was effected on the 2nd October, with the comparatively trifling loss of two killed and eleven wounded-a result which was due to the careful and scientific dispositions of Colonel Na pier, under whose personal guidance the operation was conducted. Three guns were taken and burst ; their carriages destroyed, and a large house in the garden, which had been the enemy's stronghold1 was blown up.

With a view to the possibility of adopting the Cawnpore Road as my line of communication with Alum Bagh, Mojor Haliburton, 78th Highlanders, com­menced on the 3rd to work from house to house with the crow-bar and pick-axe.

On the 4th, this gallant officer was mortally wounded, and his successor, Major Stephenson, of the Madras Fusiliers, disabled. During the whole of the 5th these proceedings were continued; but on the 6th they were relinquished, it being found that a large mosque, strongly occupied by the enemy, required more extensive operations for its capture than were expedient; therefore, after blowing up all the principal houses on the Cawnpore Road1 from which the garrison hacl been annoyed by musketxy, the reconnoitring party gradually withdrew to the post in front of Phillips' Garden, which has since been retained as a permanent outpost, affording comfortable accommodation to Her Majesty's 78th Highlanders, and protecting a considerable portion of the entrenchment from molestation, besides connecting it with the palaces occupied by General Havelock. During the foregoing operations, the enemy, recovering from their first surprise, com­menced to threaten our positions in the palaces and outposts by mining and assaults. As there were only a few miners in the garrison, and none with the field force, the enemy could not be prevented from explodino- three mines, causing us a loss of sevenl men; and on the 6th they actually ;enetrated into the palace in considerable numbers. But they paid dearly for their temerity, being intercepted and slain at all points. 'l'heir loss on that day was reported in the city to have been 4,50 men.

A company of miners, formed of volunteers from the several corps, was placed at the disposal of the Chief Engineer, which soon gave him the ascendancy over th~ enemy, who were foiled at all points, with the loss of their galleries and mines, and the destruction of their miners in repeated instances.

Oli TllE DEFENCE OF LUCKNOW. 57

The Seikhs of the Ferozepore Regiment have zenlously laboured at their own mines, and though separated only by a narrow passage (16 feet wide) from the enemy, ha,·e, under the guidance and direction of' the Engineer Department, defended and protected their position.

The outpost of Her Majesty's 78th Highlonders, under Captain Lockhart, bas also been vigorously assailed by the enemy's miners. Its proximity to the entrenchment made it convenient to place it under the charge of the Officiating Ganison Engineer, Lieutenant Hutchinson, under whose skilful directions the enemy have been completely outmined by the soldiers of Her bJnjesty's 78th Regiment.

I am n.wnre of no parallel to our series of mines in modern war; 21 shafts, aggregating 20:1 feet in depth, and 3,291 feet of gallery, have been executed. The enemy advanced 20 mines against the palaces and outposts I of these they exploded three, which caused us loss of life, and two which did no injury; seven have been blown in; and out of seven others the enemy have been drh,en, and their galleries taken possession of by our miners ;-results of which the Engineer Department may well be proud. The reports and plans forwarded by Sir Henry Havclock, K.C.B., and now submitted to His Excellency, will explain how a line of gardens, courts, and dwelling houses, without fortified enccinte, without flanking defences, and closely connected with the buildings of a city, has been maintnincd for eight w~eks in a certain d~g1•pe of s2curity; but not­,vithstandiug the close and constant musketry-fire from loopholed walls and windows, often within 30 yards, and fl'Om every lofty building within rifle-range, nnd notwithstanding a frequent though desultory fire of round shot and grape from guns posted at various distances, fl'Om i0 to 50r) yards! This result has been obtained by the skill and courage of the Engineer and Quartermaster General's Departments1 zealously aided by the brave officers and soldiers who have displayed the same cool determination and cheerful alacrity in the toils of the trench and amidst the concealed dangers of the mine that they hnd J)re­viously exhibited, when forcing their way into Luckuow at the point of the bayonet and amidst a most murderous fire.

But skilful and courageous as have been the engineering operations, and glorious the behaviour of the troops, their success has been in no small degree promoted by the incessant and sdf-denying devotion of Colonel Napier•-who has never been many hours absent by day or 11ight from any one of the points of operation-whose valuable nd\·ic~ has ever bec.·n readily tendered and grate~ fully accepted by the executive officers-whose earnestness and kindly cordiality have stimulated and encouraged all ranks and grades, amidst their harassing difficulties and dangerous labours.

I now lay before His Excellency Brigadier Inglis's report of the proceedings in the garrison. since its relief by the force under my command, since the capture of the enemy's batteries, and the occupation of the palaces nnd posts.

The position occupied by the Oudc Field Force relieved the garrison of tho entrenchment from all molestation on one-half of' the enceinte-that is from the Cawnpore Road to the comm~nccmcnt of the rh'er front i and the garrison, reinforced by detachments of the 78th and Madras Fusiliers, was enabled to hold as outposts three strong positions commanding the road leading to the Iron

• Now Major General Sir R. Napier, K.C.B. n

58 ON THE DEFENCE OF LUCKN0W.

Bridge, which havo proved of great advantage, causing much annoyance to the enemy, and keeping their musketry fire at a distance from the body of t_he place.

'l'he defences, which have been barely tenable, were thoroughly repaired, and new batteries were constructed to mount 13 additional guns.

The enemy, after the capture of the batteries, adopted a new system of tactics. 'l'hcir guns were withdrawn to a greater distance, and disposed so as to net not &"'ninst the defences, but against the interior of the entrenchment.

0 "fhe moment they were searched out and silenced by our guns their position was changed, so that their shot ranged through the entrenchment; and but for the desultory nature of their fire might have been very destructive."

REPORT ON THE ENGINEERING OBERATIONS, BY NIAJOR CnmnrELIN, C.B.,

BENGAL ENGINEERS,

Lucknow, November 12th, 1857.

I hnve the honour to submit for the information of Br.igadier General RaYelo::-k, C.B., Commanding the Oude Field Force, a brief narrative of the engineering operations that have been carried on at the palace and gardens of the Chutter l\funzil since our occupation of the same up to the present date.

2. Instead of presenting this sketch in the shape of a journal (for which indeed my data are very incomplete), I have determined upon adopting the more simple and intelligible plan of describing the operations under the four following heads, viz. :- 11 General DefensiYe Operations;" 11 Operations at advanced Garden;" "Mining Operations," and" Final Offensive Operations."

'l'he two accompanying Plans, marked A and B, will illustrate the Report.•

GE~ERAL DEFENSIVE OPERATIONS.

3. It would serve no useful purpose to swell this report, by detailing all the numerous petty operations that fall under this head, such as "Preparing roads for passag~ of guns;'' " Piercing loop-holes in walls of houses and courts; 11

'' B_urricading passages and isolated doors or windows;" "Opening out communi­cations between posts and picquets;" "Providing screens at various places against mui;ketry fire," &c., &c., &c.; but the following more important works are deserviug of separate notice:-

l&t.-On the 8th October, the rebels attacked one of our advanced picquets at A; they were repulsed immediately with loss to themselve.!i; but it was consi­dered advisable to disconnect the close communication that existed between their position and out's. 'J'o effect this end a charge of 200 lbs. of powder wss laid, under the superintendence of Colonel Napier (Chief of the Staff), at much risk and with considerable difficulty, in a vaulted chamber, under some apartments

It has not been considered necessary to reprint these plates, but the letters of refer~nce have been inserted in the Plan at the end of the next Paper.-ED.

ON THE DEFENCE OF LUCKNOW. 59

ndjoining our position and occupied by the enemy. The result of the explosion was most satisfactory ; the positions were entirely separated, and a clear view opened down the Khas Bazaar Street.

2nd.-The roof of the picquct above alluded to, serving as a post and road of communication to other points, being exposed to the fire of a 9-pounder gun, posted in the Khas Bazaar Street at a distance of 300 yards, a sand-bag parapet, about 8 feet thick at the base nnd 4 feet at the crest, was erected in one night along the end of the roof, and has since remained proof against the repeated rounds that have been fired at it from the gun.

3rd.-A battery B for two 9-pounder guns has been constructed at the end of the lane to the south of the Lall Bagh, to sweep down the lane, in the event of the enemy forcing the advanced barricade at C.

4th.-A barricade D, 72 feet in length, composed of boxes, doors, and tent poles, with an embrasure for a single gun, has been constructed at the north­west corner of the Pyne Bagh, connecting the Lall Baradurree with the J ai1. This barricade serves the double purpose of a defence against any attack of the enemy by the Pyn& Bagh; and as a covered way from the palace to the road that runs direct by the Clock Tower to the Baillie Guard entrenchment.

Otb.-A barricade E, similar to the above, GO feet in length, but without a gun embrasure, has also been constructed close to the most advanced picquet on the water face of the Lall Bagh, to prevent the passage of the enemy down the broad terrace between our palace position and the river. There is a corres­ponding barricade further up stream, near the Baillie Guard entrenchment.

6th.-The whole of the exposed doors and windows of the Lall Bnradurree, Furrad Buksh, and Cbutter 1"1unzil Palaces haYe been provided with shot­proof barricades, composed of boxes and sand-bags. 34~pounder shot, fired from a distance of about 400 yards, have twice struck the top or weakest part of one of the Lall llaradurree bardeadcs, at a htight of 10 feet. The sand-bags were on both occnsions thrown in ward8, but the shot foll harmless on the ground close to the foot of the barricade. At a height of 8 feet those barricades might be considered quite shot-proof.

7th.-On the terrace of the J\Iosque F, three strong lines of barricades, composed of doors, sand-bags and tent poles, have been constructed, in order that the utmost extent of the Mosque might be defended, in the event of the enemy destroyiug any portion of it before our countermines could be completed. 'Jhe enemy succeeded in blowing down the corner of the Mosque (at A); but the explosion tended rather to strengthen than weaken our defensive position, nnd did not reach even our most advanced line of barricades. A shot-proof parapet was also constructed along the east front of the Mosque, as a protection against a battery G tha.t the enemy commenced, but have not as yet completed. at a distance of 200 yards down the Cheena Bazaar.

Sth.-The gateway and picquet house at the end of the lane to the south of the Lall Bagh have been strongly barricaded.

9th.-A Cavalier battery for one heavy gun has been commenced immediately behind the above-mentioned gateway, and is in cow·se of construction.

60 ON TUE DEFE~CE OF LUCKNOW.

OP£RATI0NS AT ADV.\NCED GARDEN.

4. On the 5th of October, the enemy brenched the south face of the advanced garden at If, and ma<le an unsuccessful attack at that point. A retrenchment (a) was immediately constructed, and has since been 1-cndered shot-proof. A trench (b) facing the breach, nnd extending from the house in the centre of the garden to the east wall, was also constructed for the she1ter of a strong guard. A third trench (c) for a strong guard, with a communicating trench (d), from the gate of the garden, were at the same time constrncted, and also a battery (e) for two 9-pounder guns to sweep the breach JI.

Shortly after having formed the breach H, the enemy burnt down the gate K, in the cenfrc of the east face of the garden, and enlarged the opening by n fe,v round shot. 'l'his new breach was at once barricaded, and a retrenchment (f) thrown round it, debouching from trench (b).

Subsequent to the above operations, the following works were taken in hand and gradually carried to completion :-lst. A trench of communication (g) from the gate L to the Vinery, near the right advanced 11icquet M. 2nd. A trench of communication (h) from the Vinery, to the south-west corner of the garden house. 3rd. A trench (i), with double parapet and traverses, running parallel to the north wall from trench (c) to the east wall. 4th. A trench (k) with traverses, running 11arallel to cast wall, and connecting trench ( i) with retrenchment (f). 5th. A battery ( l) at the north-west corner of the garden house, for three guns to bear upon the breach H, and to oppose two batteries that the enemy had erected outside and opposite to the southern end of the east wall. 6th. A battery (m) for two howitzers to a~sist the foregoing one. 7th. A battery (tl) for two guns to sweep any breach that the enemy might mnke in the walls, near the north-east corner of the garden. 8th. The doors and windows of both centre garden house and picquet house M have been strongly barricaded with sand-bags and boxes. And lastly, a. C;nalier Battery, with six embrasures for heavy guns, to sweep the opposite bank of the river, and the several posts of the enemy, in front of the garden, has been commenced and is drawing to cmu­pletion.

The whole of the trenches arc unrevetted, and were constructed by simple sapping. The batteries are revetted with boxes and doors.

The working parties employed were small, and were composed of men totally untrained to such duties, viz., European and Nath·e soldiers drawn from the different Uegiments, and Doolie Bearers.

MINING OPERATIONS,

. The enemy very sbortly after our occupation of the Palaces, showed a disposi­t w'.1 to nnno! u~, as much as possible, by their mines. On the 5th October (as lJetore mentioned), thry effiictcd a breech in the south wall of the advanced go.rdcn. On the 11th idem, they breached a portion of the boundary wall on the east face of the Sikh position, and on the 17th idem, they succeeded in de­&trnying an upper story room, in front of the l\Iosque F. Our limited supply

•

ON THE DEFENCE OF LUCKNOW. 61

of gunpowder pre,·cntcd our retaliating by offensive mines; so we determined upon encircling the whole of that portion of our position, open to attack by mines, with a system of dcfensi\·e. or listening galleries, from which we could discover the np11roach. of the enemy's miners, and break into their mines or destroy them by small charges of powder before thC'y could nach our boundary. Volunteer miners were accordingly called for from lhe several regiments, and on the 18th of Octobc1· we started work at five mines, with a force of Gl European soldiers and 48 Sikh sepoys. Subsequently this force was strengthened by three other gangs, consisting of 54 doolie bearers and gun bullock drivers. The number of tthafts and galleries that have been completed are as follows:-

Nine in the Sikh position (marked 1 to 9 on Plan), giving an aggregate of 73} fc•t of shaft, and 540/ feet of gallery.

Four for the protection of the :Mosque picquet A, and adjacent buildings (marked 10 lo 13). giving 32\ feet of shaft and 585\ feet of gallery.

1\vo for the protection of the buildings along the lane to the south of the Lall Bagh (marked 14 and 15), containing 16 feet of shaft and 514 feet of gallery.

Two, marked 16 and 17 for the lane barricade, and south wan of advanced gar<lcn, with branches for offensive mines, ghing 15 feet of shaft and 765 feet of gallery.

Two, marked 18 and 19, for the east face of garden, giving 16 feet of shaft, and 387 feet of gallery.

Total of shaft 152 feet; ditto of gallery 2,791¼. 'l'he shafts average 8 feet in depth, and the general section of the galleries may

be set down as 3 feet in height by 2 feet in breadth, with an arched roof. We found the soil to be generally light and sandy; still the greater portion of the galle­ries were run without casing, although occasionally it was found absolutely neces~ snry to resort to rough open casing. l may here mention, as an extraordinary fact that two galleries were run respectively to lengths of 298, and 192 feet, without the aid of air tubes i in the latter the lights burned well, but in the former the men were obliged to work in the dark, nnd were somewhat (though not greatly) affected by the foulness of the air. In working these, we occasionally withdre,v the miners for an hour or two, in order to purify the galleries. The daily pro~ gress in each gaJlery ,,aried from 13 to 20 feet.

'fhe utility of the above.mentioned galll'ries has proved most marked. On eight different occasions the enemy were heard mining towards our position. ,ve waited patiently and quietly until their miners broke into our gallery. ,re then fired on them through the opening, wounding several, and in every instance we captured their galleries and tools, and then destroyed the former without using any powder. On two other occasions1 when the enemy were heard approaching, we commenced running out short branches from our own galleries, in order to lodge charges for blowing in those of the enemy. Their miners in both enclosures abandoned their galleries. Our success has so alarmed the enemy that they have latterly been afraid to approach near our position, and have twice exploded charges at ridiculously long distances from the works that they intended to destroy, indeed nearer to their own buildings than to ours. I may say that sir1ce we commenced our listening galleries, the enemy have failed to do us any injury with their mines, and that our exposed front has remained 1:er:'ectly secure.

•

ON TIIE DEFENCE OF LUCKNOW.

Our offcnsi"e operations that nre now in progress, and which I trust "ill p1·0,·c conclusi,·e, will form the subject of n future communication, in which I will take the op1mrtunity of bringing to the notice of the Brigadier General Commanding the names of those officers nncl men of the department who have rendered good service.

I bnYe, &c., W. A. CilOMMELlN, Captain,

Chief Engineer, Oude Field Force.

REPORT ON THE ENGINEERING OPERATIONS, BY MAJOR CROMMELIN, C.Il.

Camp Alum Bagb, November 25th, 18.57. Sm,

Jn continuation of my letter elated 12th instant, I have the honour to report, for the information of the :Major General Commanding the Oudc Field Force, upon the "Final Engineering Offensive Operations" at the palace and gardens of the Chuttur Munzil.

The Cavalier Battery, alluded to at the conclusion of my previous report, was completed during the night of the 13th instant, and was armed with the heavy guns on the morning of the 14th, viz., the day originally appointed for the storming of the Hern Khana, Engine-house, and King's Stables.

During the night of the 13th, 29 charges of powder (each 25 lbs. in weight) were laid in chambers that had been previously prepared for them, under the foundation of the east face of the advanced garden wall, and immediately in front of the Cn'\'alier Battery. These charges were intended for the demolition of that part of the wall that screened the Engine-house, Stables, and the other adjacent buildings, that were to be breached from the guns of the battery. I would here remind you that our attack wns postponed from the morning of the Hth to that of the 16th. The charges of powder were thus exposed, in com­mon canvas bags, for more than forty-eight hours, to the damo.ging influence of a very damp sandy soil; so that when they were exploded, their effect, owing to the deterioration of the powder, was only sufficient to shake and split the wall in several places, and to form a small breach. The wall, however, was so much injured, that the artillery had an easy task in battering down ns much as was necessary. The charges, I may mention, were half as large again as those recommended by Sir \V. Pasley ( our best practical authority on this as well as most other points of engineering detail), and were such as had been successfully used by myself, at Peshawur, in a precisely similar case.

Du,ing the night of the 12th and 13th, the trench (d d) was widened for the passage of guns; screens were also constructed in the ad,·anced garden; and other precautionary measures to.ken, to protect our force against any musketry fi1'e that might be poured in through the breaches in our own wall.

ON THE DEFENCE OF LtlCK:SOW. 63

During the 15th the three mines that had been prepared for tho formation of breaches in the Hern Khann, were loaded and tamped. ThC'se mines were sprung on the afternoon of the 16th. 'l'hnt at the north-west corner of the building effected the breach by which the right and centre columns of attack entered. Lieutenant Hall, in his report, erroneously states that this breach was made by the IS-pounder gun at the barricade.

The centre mine failed to explode, on ing, I imagine, to some wet sand having been dislodged from the roof of the mine, by tho concussion of our artillery, and having fallen upon the powder hose.

'fhe left charge, which was the largest, exploded; but it pro,ed to be 10 feet short of the building, and consequently effected no breach or injury. 'fhis error in the position of the charge is not to be wondered nt, when it is considered­lst, that we could not, by the most careful survey, satisfy ourselves as to the exact position of the Hern Khana; and, 2ndly, that we could not survey the mine itself with the prismatic compass, ns no lights \'\'ould burn, owing to the foulness of the air near the end of a gallery that had been carried to the (I believe) unprecedented length of 289 feet, without the aid of air-pipes,

On the morning of the 16th everything was ready for the attack upon the Hern Khana, Engine-house, and Stables. Copies of instruction, the details of which had bePn prepared by myself, from memoranda drawn out by Colonel Napier (Chief of the Staff), were handed over to each of the five officers com­manding the storming parties, and to the engineer officers accompanying them; and these instructions were further explained, by the aid of plans, to several of the commanding officers.

For an account of the operations of the storming parties, I must refer to the enclosed reports (in original) of Lieutenants Hutchinson, Russell, Limond1 and Hall, with the remark that the duties of the officers under my command appear to me to have been rapidly and efficiently carried out.

I must also refer to a separate report by Lieutenant Hutchinson, directing engineer, upon the engineering operations, from the 16th November to the hour of our evacuation of the Bailey Guard Entrenchment and the Chuttcr Munzil Palace-confinement to my quarters owiug to an injury of the leg, having prevented my su1)erintending them personally.

It now remains for me to bring to the favourable notice of the Major General Commanding, those officers and men of the En).{ineer Department who have rendered good service; and, in the first place, I trust it may not be considered out of order that I hereby thankfully record my acknowlt'dgment of the assistance that has always been afforded me by my cxperiencC'd brother officer, Colonel Napier, Military Secretary nnd Chief of the Staff to Major General Sir James Outram, G.C.B., who, notwithstanding the pressure of his other important duties, was ever ready to aid me with his valuable counsel and advice, to meet my constant demands for workmen and materials, and to superintend and direct the works during the last month of our operations, when I was disabled from personally superintending them myself. .

Lieutenant G. Hutchinson, of the Engineers, deserves very great credit for the n~ry nble manner in which he discharged the duties of Directing Engineer of lhe works, during the last ten days of our operations. His sen-ices, as one of the engineers of the original garrison1 will be duly reported by the pro:pe1· authol'ity.

61 ON THE . DEFENCE OF LUCKNOW.

Lieutenant Russell, of the Engineers, has rendered me very efficient nid as Drignde Major of Engineers; his constant and unwenrying exc1'tions, both by night and by day, merit my best thanks and the highest praise.

Lieutenant Limond, the only other Engineer officer under my command, has also proved himself a ,•ery able and energetic officer, and has rendered very excellent service. To him, and to Lieutenant Russell, was entrusted the general &upervision of all the works from the time that I was disabled until the nppolllt~ mcnt of Lieutenant Hutchinson as Directing Engineer-a period of about three weeks.

'l'he officers and volunteers that have acted in the capacity of Assistant Field Engineers have, without exception, given me thci1· best and readiest assistance i but I may ,vith justice more conspicuously notice the names of Captain Oakes, St.h Native Infantry i Lieutenant Hall, 1st Ilenga.l Fusiliers; Mr. Coldsworthy, Volunteer CaYalry; and of l\Ir. Cavanagh, Superintendent of the Chief Commis­sioner's Office.

Sergeants Duffy and Connell, Assistant Overseers in the De1mrtment of Public ,v orks, haYe proYed most useful, and their duties in supervising workmen and collecting materials, &c., &c., ha.Ye been most cheerfully and efficiently per­formed.

I cannot close this report without noticing, in the most favourable manner, the im1>0rtant services performed by the under-mentioned soldiers, as superin­tendents of miners :-

,, ,, Banet ta, . , . Acting Sergeant Cullimore, }

,, ,, Farrer, Her 1':IaJcsty s 32nd Regiment.

Corporal Dowling, ,, Hosey, Madras Fusiliers.

Prh·ate Ilaylan, Her Majesty's 5th Fusiliers. Their duties have been of a very dangerous and arduous character, and haYe

invariably been performed to my complete satisfaction."

I have, &c., W. A. CR0:11MELIN, Captain,

Chief Engineer, Oude Field Force.

EXTRACT FROM A MEMORANDUM OF \V ORK EXECUTED AT CAPT. LOCKHART'S

PosT, FROM THE FIRST POSSESSION OP IT UNTIL THE 21ST OF Nov., 1857,

BY LIEUT. G. HUTCHINSON, BENGAL ENGINEERS.

Banicades were at once and primarily erected at all outlets, and loop-holes cut along all the walls.

Doorways of communication were opened between the three main houses, which originally were distinct lmildings, and such arrangements made as enabled us to command to the utmost the ruins on the right and left of our position.

A cannon-proof barricade was en•cted across the Khas Bazaar communicatinn­with the post of the 84th, and an embrasure opened through' it for a f,Wl : :

~ccoud barricade was afterwards placed across the Cawnpore Road.

ON TllE DEFENCE OF LtTCKNOW. 65

The :nemy commenced mining agninst UB nt II on the left of our position, ab?l~t 1:11x days after our occupying the potit. ,ve sunk a shaft, prc1mratory to dnnug a gullcry, to meet them; but before we could complete the shaft, the enemy exploded a very large charge of powder, some 10 fCet short of ow· outer cnclo~ure wnll, which had the effect of shaking do,vn the wall and filling up om· shaft, by the masses of earth thrown into the air and descending into our shaft. I regret to say we lo.-.t one man in this shaft. By some fatality, though the men on duty and at the mine saw the enemy's train burning, and volumes of sm.okc iissuing out of the hou'l;es1 from which they knew the enemy were mining, they did not IDO\'C from the ~pot, but merely sent to report to their officer. ,ve were pre1mred for the <.'xplosion, and bnd the enclosure already ban-icaded off, so that the enemy gained nothing by the mine.

From this time up to within the last :six days, we have been almost constantly at work day and night, countermining against them.

Our general success has been ,ery good, haying held our ground with an cx.pcncliture of but 200 lbs. of powder, and resisted numerous attacks of the enemy's miners.

On two 1mrtieular occasions our success was more than usual. A gallery, dri\'en from our shaft C, intercepted a gallery of the enemy's1 and our explosion complctcl~· cut off.' some 12 feet of it; so ihat the next morning, on breaking into the portion so cut off, we dng out, or rather dragged out, fom· dead bodies, the enemy's miners having been completely cut off in a tomb, as it were, for tho gallery they were in was not broken down, but sto11ped up by our explosion.

In the other case our operations commenced from shaft D. ,vc broke into their gallery some 12 feet from our wall about 12 o'clock at

night, and Sergeaut Day, om· Sn1)erintencling Miner, remained below, assisted by others, holding the entrance to their gallery until I arriYed.

On entering the enemy's gallery, I took Co111oral Thompson, of the 78th High4

landers, with me, and obserYing the apparently great length of the enemy's mine, proceeded cautiously to extinguish the lights, so as to keep mu·sehes in darkness as we advanced. At this time 1he enemy were in the mine at or near their shaft, which, contrary to their wmal practice, they evidently wished to hold wiinjm·ed. They usually fill them in at once when we take their galleries.

I proceeded, ex.ti.nguishing the lights, nntil I distinctly saw the enemy at the far end: and to advance further would be to ad\'ance in a blaze of light. I therefore lay down and waited, as our preparations aboYe, carried on under Lieutenant ·Tulloch, were not yet ready. ,Yhilst lying there, I saw a sepoy with musket at trail adyancc down the mine, and when within 40 feet of him, fired at him. l\Iy pistol missecl fire, and before Corporal Thompson could hand me his pistol the sepoy had retreated. After remaining some time longer, I placed another man with Cor1)oral Thompson, and went up to get an officer down, as I felt it required a very steady man down there to sup1iort us. 1Yhile we were laying the charge, and making various arrangements, which utterly precluded our watching against an enemy's. advance _at the ~a.me time, Lieut. Hay, of the 78th Highlanders, then commanding the p1cquct1 kindly vo!unteered and took up my old 1wst. Lieutenant Tl1lloch and Sergeant Day qmckly got

I

66 ON THE DEFENCE OF LUCKNOW.

the powder down, and all nrrnngcmeuts h(rdng been made, we withclrew Lieut. }fay behind the partial bunicndc we had formed i nnd whilst here, still watching with Corporal Thompson, he got two shots at another man who attempted to come down the mine, and npp:1rcntly wounded him. The enemy made no more attempts to come down the mine, but went outside their building, and came over our heads, appurent1y with the intention of breaking through. After a quarter of an how·'s "~alking oyei• head, they, I conclude, could not find the direction of the mine, and retreated into the house.

Our charge of 50 lbs. which I laid outside our barricade at a point 82' along the enemy's gallery, was soon tamped, and the charge fired by Lieut. Tulloch. The charge being laid with nine feet of sand.bag tumping behind it, and none in front, the main foroe of the powder acted towardS the enemy's shaft, but it destroyed the gallery for 40' towards us, leaving us a length of 40' to use as a listening gallery. I deduce the enemy's mine to be 200 feet long and upwards, from the reconnoitring of Lieutenant Hay and myself before we commenced laying our charge, and from the position of the houses it came from. The gallery had numerous air.holes and was thoroughly ventilated.

I was much indebted to Licutenan t Hay and Corporal Thompson in this business, and also to J,ieutenant Tulloch1 who himself also fired the mine-a somewhat difficult task, as om· hose beiug short, he had to retreat some sixty feet through the enemy's gallery and ours, and then out of the shaft. Such is a brief account of our mining operations."

67

PAPER X.

REPORTS ON THE ENGINEERING OPERATIONS AT THE SIEGE

OF LUCKNOW, IN MARCH, 1858,

BY MAJOR GEN. SIR R. NAPIER, K.C.B., COL. HARNESS, C.B.,

AND LIEUT. COL. LENNOX, ROYAL ENGINEERS.

REPORT FROlll THE CHIEF ENGINEER, NOW MAJOR GENERAL SIR R. NAPIER, K.C.B., TO THE CHIEF OF THE STAFF.

La llfartiniere, 31st March, 1858. SIR,

I have the honour to submit a Report of the Engineer operations at the Siege of Lucknow, accompanied by a map, and also a Report by Colonel Harness, commanding the Royal Engineers, of the operations in detail which were con­ducted under his immediate directions by officers of the corps under his command.

The City of Luckuow stretches in an irregular form on the right bank of the Goomtee, for a length from east to west of nearly five miles, and an extreme width at the west side of one and-a-half miles; the east side diminishes in width to less than one mile.

2. Two bridges, one of iron, and the other of masonry, span the Goomtee, leading the traffic of the country from the north of the Goomtce into the heart of the city.

A canal of deep and rugged section, enclosing the city on the east and south sides, bears away to the south-west, leaving the approach to the west side of the city open, but intersected with ravines; towards the north-east, where the canal joins the Goomtee, its banks are naturally shelving and pa~sable.

The city is too extensive to be commanded by any single point, and has no such predominant feature as would imperatively direct the attack.

The important positions are:-1. The Kaiser Bagh (A) or Royal Palace, about 400 yards square, containing

several tombs and ranges of buildings; not originally fortified, but strengthened since the last occupation of the Resid1mcy by British troops.

2. 'J he Fcrhad Bux ( B), and adjoining palaces, occupied by the British troops under Outram and Havelock.

3. The Residency ( C). 4. The ruins of the ancient Fort, calkcl the Muchee Bowun (E), commanding

the !\fasoury Bridge, and ::,ituakd on the south sicle of it.

68 ON THE ENGINEERING OPERATIONS AT TllE SIEGE OF LUCll'.NOW,

5. A series of strong buildings; the Jumiuia Bugh (F), the Shesh ?ifahal• (G), and Ali Nukki Khnn's Uousc (FI), extending to the west along the right b[mk of the river, and more or less surrounded by streets and houses.

6. The lmambnrah and a runge of palaces (I), stretching from the Kaiser Bagh eastwards towards the canal.

7. A mile nnd a hnlf west of Ali Nukki Kbnn's House, lies the Moosa.h Bagh (.K), a walled enclosure and country house.

8. On the east side of the city beyond the canal, stands the Martiniere (L ), a fine range of buildings.

9. On the brow of a table land overlooking the Martiniere and the eastern suburbs, is the Dilkoosha House.

In recommending the east side for attack, I was guided by the following reasons:-

The west side presents a great breadth of dense, and almost impenetrable city, resting on the strong buildings on the rh·er bank. After OYercomiog these obstacles, there would have remained the Kaiser Bagh, with the enemy's prin­cipal defences still to be reduced.

The east side offered-lst, the smallest front, and was therefore the more easily enveloped by our attack; 2ndly, ground for planting our Artillery, which was wanting on the west side; and 3rdly, it gave also the short('st approach to the Kaiser Bagh (the Royal Garden), a place to which the rebels attached the greatest importance; more than all, we knew the east side and were little acquainted with the west.

'l'he enemy, profiting by experience, had strengthened their defences by works exhibiting prodigious labour. Sir Colin Campbe1l's former route across the canal, where its banks shelved, was intercepted by a new line of canal of very formidable section, flanked by strong bastions. This line of defence was continued up the canal beyond the Char Bagh Bridget ( M ), more or less complete, and the banks of the canal, as before noted, were scarped and impassable.

A strong battery for three guns, resting against a mass of buildings ( N), called the Huzrut Gunj, supported the outer line, at the junction of three main roads.

A second line of bastioned rampart and parapet rest('d with its right on the Imambarah (0), a strong and lofty building; thence embracing the l\less House ( P), it joined the river bank near the Motee Mahal ( R ).

A third line covered the front of the Kaiser Bagh ( S). The enemy were represented to ha'\"e about 100 guns, a report which was

doubted, but has proved quite true. 'l'he bastions on the outer line of defonce were not fully armed; the enemy

seemed waiting to ascertain our real point of attack, before bringing forward their guns.

A 11 the main streets were also commanded by bastions and barricades and every building of importance, besides being loophold, had an outer work1 pro­tecting its entrance.

• These buildings are !o the west of the Muchee Bowun and are shewn in the plan opposite to page 381 Vol. IX, of this Series.-Eo.

i" The Char Bagl1 Ilridge is about 3,000 ycls, to the west of the Dilkoosha Brillge.-En.

ON TUE ENGINEERING OPERATIONS AT THE SIEGE OF LUCKNOW. 69

It _was ascertained, as one part of the city after another fe11 into our hands, thnt it hnd been the intention of the enemy to offer a very determined resistance even nftc1· their outer lines i-hould be taken. Houses far in the depths of th; commercial parts of the city were found carefully defended with mud walls and parapets, se,·eral mounting guns; and in addition to vast quantities of gun. powder found lying in large buildings, almost every house hnd its own small supply.

MEANS FOR THE ATTACK.-Ordnance.

Ouns .... . Naval Brigade,

Ditto ................................. . Howitzers .....

8-in. 24 pdrs.

8-in.

6 8 2

Artillery. Guns . . . . . . . . . . . . . . . . . . . 24-pdrs. 8 Ditto.................... 18 ., 8 Ho,vitzers ........ , •......•.....•... , 10-in. 4 Ditto...................... 8 ,. 6 Mortars....... .. .. .. .. .. .. . . .. . ... 43

A complete Engineer Park, with materials for two ca.sk bridges, calculated to bear the heaviest ordnance.

Having in my possession a very accurate survey of part of the city and its em·irons, by the lntc Lieutenant l\Ioorsom, of Her Majesty's 52nd Regiment, and being aided by the excellent information received from the Inte1ligence Department, attached to 1\Iajor General Sir James Outram, G.C.B., I was enabled at a very early period of the operations to determine which side of the city offered the greatest facility to our attack.

Formidable as the defences thrown up by the enemy on the eastern side of the city were described to be, it still appeared most evident that they were in reality obstacles less difficult to be overcome than the heavy and dense portions of the city to the '\Vest; and I would add here that though I hardly gave full credit to the native statements as regards the sections ancl extent of the enemy's works, yet it has proved on inspection that the intelligence given me was remarkably good and clear.

The side of attack being fixed, the two next steps of primary importance were, after taking up a position in the Dilkoosha Park, to bring a direct fire on those points in the enemy's fortifications in rear of the canal the fire from which would affec.:t the line by ,vhich we should cross them, and to enfilade those fortifications from the left bank of the Goomtee.

These two operations being completed, and the first line of fortifications in our possession, the next step was to establish ourselves at Banks's House and the D Bungalows (DD) and from that position to reduce the Begum's Palace (1').

A glance at the map will show that this palace is the extreme point of a line of strong buildings, which extend to the walls of the Kaiser Bagh, and secured us a covered way for our safe but irresistible progress into the heart of the enemy's position, turning successfully their second and third lines of fortifica­tions, and avoiding entirely the fire of their artillery.

I.

70 ON THE ENGINEERING OPERATIONS AT TlIE SIEGE OF LUCKNOW.

The elevated gateways and roofs of the1m buildings, commanding the ground on either flank, would give us the choice of positions for establishing our bat­teries to bombard the Kaiser Ilagh and other parts of the town.

Should the fall of the Kaiser Bagh not entail the abandonment of the city by the enemy, the successive reduction of their strong positions on the banks of the river would be necessary.

Much importance was attached to vertical fire, for which the ample provision of 43 mortars was made in the Siege Train.

The interval which elapsed between the nnival of the Engineer Establish­ment at Alum Bagh and the commencement of the attack wus most valuable, and was profitably employed in preparing a large supply of gabions and fascinea, and proving and perfecting the cask bridges; also in practising the Department in the rapid construction of batteries, field powder magazines, &c., &c.

Six guns, forming Battery No. 1 L, bad been placed in front of the Dilkoosha, to protect the camp, to keep down the fire of the enemy's batteries in their first line of fortification, and check two or three guns that the enemy had advanced to the northern angle of the l\lartiniere.

The fi rst operation of the siege was the construction of two bridges of casks over the Goomtee, below the Dilkoosha House, on the night of the 4th and morning of the 5th March. The officers of Engineers employed were:­Major Nicholson, and Lieutenants ,vynne, Pritchard, and Swetenham, Royal Engineers, and Lieutenant Smyth, Bengal Engineers.

On the 6th, General Outram's Division crossed to the left bank of the Goomtee, and encamped on the Fyzabad Road.

On the 7th, it was supplied with the following ordnance for the siege opera­tions on the left bank: four 24-pdrs., four 18-pdrs., four 8•in. howitzers, ten s.in. mortars; to which were added five 10.in. mortars by order of His Excel­lency the C01nmander•in-Chief.

Ou the 8th, the enemy's fortifications were reconnoitred from the left bank of the Goomtee by His Excellency the Commander-in-Chief, accompanied by the Chief Engineer, Captain Taylor, and l\lajor Nicholson, R.E. During the night a battery for ten guns, en barbette, No. 1, R, was constructed at the Kokral Bridge, to command the enemy's position near the Race Stand, and opened fire

Major Nicholson, R.E. Li eut. ,vatson, B.E.

Swetenham, R.E. Nuthall, Pun. Prs.

at day-break on the 9th. On the same day General Outram, after defeating the enemy, occupied the whole of the left bank as far as the Badsbab Bagh, and established Battery No. 2, R, of twelve guns, to enfilade the enemy's first line of fortifications. No

cover was required. The enemy made no reply, and abandoned their defences. During the night of the 8th, batteries 2, L, and 3, L, the former of four guns,

to batter the ~Iartiniere, and the latter of four guns, to silence the enemy's right batteries, were prepared and opened fire early on the 9th. C~pt. Le_nnox, R.E. Two guns of the Naval Brigade were placed under Lieut. ir~ch:rd, :·~· natural cover, to fire on the Martini~re, in flank and

L:n~: ;_'E. · · reverse. After a severe cannonade the l\Iartini€!re Forbes B E was taken on the afternoon of the 9th with little Thacke1ra;, 13,E. resistance from the C'ncmr, and a trifling loss.

ON THE ENOINEERING OPERATIONS AT THE SIEGE OF LUCKNOW 71

Lieut. Beaumont, R.E. Hon. A. Fraser, B.N.J.,

attached to Engineer Brigade.

Lieut. Lang, B.E. Forbes, B.E.

Late in the afternoon the first line of fortifications, having been abandoned by the enemy, was seized by the 42nd Highlanders and Wyld's Sikhs, forming the advance of General Lugard's Division. Our troops penetrated as far ns the bridge on the :Martini€:re Road, and secured themselves in a strong position for the night.

Early on the morning of the l 0th, Battery No. 4, L, for four guns, one howitzer, and three 8-in. mortars, was established, with little labour, under natural

cover, to breach and shell Banks's House, which was taken the same morning.

Capt. Taylor, B.E. Lieut. Greathed, B.E.

Brownlow, B.E.

In the right attack, Battery No. 3, R, for four 24-pdrs., two 8-in. howitzers, and five 8-in. mortars was constructed near the Badshah Bagh, to fire upon the Kaiser Bagh.

Thus, on the morning of the 10th, the enemy's first and most formidable line of fortifications had been completely taken possession of. In the left attack, Battery No. 5, L, for four guns and eight mortars, was constructed near Banks's House to breach and bombard the Begum's Palace. In addition to this, two guns (one 8-in. gun and one 8-iu. howitzer) of the Naval Brigade, and six 5t-in. mortars, were placed in position in the D Bungalows, their fire being also directed against the Begum's Palace and the bastion in front of Huzrut Gunj.

Lieut. Greathed, B.E. Brownlow, B.E.

Lieut, Gulliver, B.E.

These batteries were erected and the guns brought up with such energy that they opened fire very soon after Banks's House was in our possession.

Communications were made between the D Bunga~ lows and Banks's House.

:Major Nicholson, R.E. On the right attack, roadways for guns were made Lieut. \Vynne, R.E. through the Badshah Bagh; and the Dilaram House ( U), was seized, and fortified under a heaYy fire from the Chutter 1\Iunzil.

During the night, a Battery, No. 4, R, of four 24-pounders and two 8-in. howitzers, and fise mortars, was erected in front of the garden of the Badshah Bogh, and opened fire at day-break on Kaiser Bogh.

Capt. Taylor, B.E. Lieut. Maunsell, B.E.

The fire from our batteries, which had been con­tinued all night, having made two practicable breaches in the compound wall of the Begum's Palace, and severely shelled the intel'ior, it was taken by assault at 3.30 P.M.

The European Bm·racks and Kuddum Russool were also occupied on the morning of this day.

A breast-work was thrown up during the night for two guns to fire at tbe enemy's bastion in their 2nd line of fortifications, which commanded the road

Scratchley, R.E. Scott, M.E. Smyth, B.E.

leading past the Begum's Palace from Banks's House. . A Serai on the right of this road had been taken at the same time as the

Begum's Palace. . A Battery, No. 5, R, for two 24-pdrs., was thrown up on the north s1~e of the

Iron Bridge, to subdue the enemy's fire from the opposite side of the bridge, and commancl the Stone Bridge,

72 ON TllE ENGINEERING OPERATIONS AT TIIE SIEOE OF LUCKNOW,

On the morning of tho 12th, the attacking force on tho left then held a strong

Lieut. ~fedley, B.E. Lang, B.E. Carnegie, B.E.

position in the Begum's Palace, the European Bru:­racks, the Kuddum Russool, the Secunclur Baghi and the Shah Nujjcf, whilst the right attack was in posi­tion from the Iron Bridge to the Badsha.h Bagh.

Openings were made during the night into Jaffir Ali's compound, V, and a

Col. Harness, RE. Capt. Lennox, R.E. Lieut. Greathed, B.E.

serai on the right of the road was occupied in advance of the one taken the preceding c,·ening, together with a mosque overlooking it.

Fam· 8-in. mortars were moved into this serai, TV, and two 8-in. mortars placed in position in its rear, also five 10-i.n. mortars Illaced in the scrai taken on the 11th inst., the fire from all being directed on the lmambarah and builclings bet,veen us and the Kaiser Bagh.

In the right attack a Battery, No. 6, R, for four 8-in. gw1s1 was erected in front of the Badshah Bagh to fire on the Residency, and on the buildings extending to the Kaiser Bagh.

Another Batter,, No. 7, R, for hrn 24-pd.rs., was erected on the left of the Iron Bridge to subdue the fire from the opposite side of the rh·er.

At day-break of the 13th1 the house and compound called Jerar-o-Dowlah's,

Colonel Harness, R.E. in advance of J affil· Ali's, was taken possession of, an entrance having been cut through solid masonry during the night.

A Battery, No. 13, L, was formed within 70 yards of the Imambarah, and in Jernr-o-Dowlah1s compound, for two guns (one 8-in., one 24-pch.) to breac-h the outer wall of the lmambarah. 'l'he guns were placed in position in the aftcr­nooni and by evening had effectually breached the outer wall and partly breached the inner.

In the right attack, four 8-in. mortars were added to the armament on the right front of the Badsha.h Bagh this day, of

10-8-inch mortars. 4-10 do. do. 4-24-pouuders. 2-10-inch howitzers. And on the city fl'Om the Iron Bridge Batteries 3-24-pounders. 1-8-inch howitzer. On the Left we had 5-10-inch mortars. 9-8 do. do. 4-.5½ do. do.

directed on the Imambarah and the Kaiser Bagh with the intermediate buildings.

On the 14th March, a heavy fu·e having been kept up all nio-ht on th breac~es until 9 A.M. of ~his day, the breachl.:!s into the Imambarnh w~re deeme: p1:act1cable, and accordingly the building was assaulted and taken at I o A.lll. without much opposition from the enemy.

((' THC f~OIN'F.ERJNG orrn,\TTON~ .\1' TTTE fl.lF.GE OF LtrrKNOW. 73

Col. Harness, n.E. The troops following- np this assault by an adrnnco Capt. Lennox, R.E. nlong- tht' road towal'd8 the Kaiser Dagh, obtained Lieut. Grtathedi 13.E. llO!Ssession of an outer court-yard of the palace itself,

Beaumont, R.E. aucl the Engineer Officer:; nnd men were busily cm• Lang, B.E. Bl'ownlow, B.E. ployecl fo1· tho 1·cnrniudcr of thi8 day in sccw·i.ng this

" rited ley, B.E. portion of the Kaiser Ilagh, nnd the l\Icss House, l:.n~ign Ogilvy, M.N.I., ~Iotec 1\Iahal, and Tara Kotee, all of whi<:h buildings

attached to ;,.1. Sappers. were found deserted by the enemy. On the right attae:k we held the same position as yesterday, our batteries

principally directing_thci.r fire on the Residency and other buildings in advance of the Clrnttcr Munzil.

The 15th found us in posscs.sion of all the prineipal buildings up to the Chutter 1\Iunzil between the city and the Goomtcc, m1cl of a. secm·c lodgmcnt in the Kniscr Ilngh.

Engineering operations were immediately directed to assist the troops through the rcmaindcr of the Yarious corn-t-)'arcls of the palace, to complete our comnrn­nication:s with the rear, nncl to clear away such parts of the enemy's works as impeded free and practic:able commu11icatiom1 bctwccn the different posts.

Lieut. Hutchinson, B.E. On the morning of the 16th, General Sir James

Outram, G.C.B., crossed the Goomtcc by the bridge of casks and di·oye the enemy from the Residency and Iron Bl'iclgc, ancl later in the cla.y seized the l\Iuchee Bowtm, Stone Bridge, and Imambarah.

Scratchlcy, R.E. Brownlow, R.E.. Champain, Il.E. Smyth, B.E. Nu1hall, P.P. Knowles, PP. ~fr. May, C.E.

Six 8-inch mortars were immC'<liatcly placed in position in the Imambarnh, and maintained :1 ~teady bombardment on the enemy's position in the city

throughout the ni_~ht: hrn naval guns and five 10-inch mortars were abo po~ted at the Resickney, and kept up a steady tire upon the city during the night of the 16th and mol'ning- of the 17th.

From this time all siege operations ccnsed, though parties of the enemy i-;till clung to the streets of the city and subw·bs, and were not dislodged till ~e:n·ral clays aftenvards.

i have no precise information eoncerning the proceedings of the force of Hi$ Ilig-hness Jung Bahadoor, which acted on the opposite bonier of the city at too great a. distance for its effects to be visible from our line of attack.

On the lith of Masch, by def,,irc of His Excellency the Commander-in-Chief, the Goorka picqucts were extended from the Char Bagh Bridge do\Tn the Cawn-11ore Road, to connect with those of the British Regiments in the Kaiser Bagh which had ad,·ancc<l half-way between the two points.

'fhe Char Bugh Bridge was rcpuircd by order of General McGregor, material being furnished for the purpose by the Engineer l'ark, and communication along the Cawn1JOre Road was completely opened.

It is now my gratifying duty to recommend to the notice of His Excellency the Conunander-in-Chicf the gallantry uml c:x:(11tio11s of my brother oflicers and soldiers of the noyal aud the Hon. Ea:-;t Inclin. Company':; E ngineers.

To Colonel Hurne~s, C'ommandi11g the Hoyal Engincersi I am very greatly imkhtcd for hi-; arraHgcml'nts for reducing the lrnambarah, for his cncrg-ctic

K

74 ON THE ENGINEERING OPERATIONS AT THE SIEGE OF LUCKNOW,

exertions and gallantry in securing the Kaisei· Bo.gh, after it had been carried by a small ndyanced party of our tl·oops, and for his very cordial co-ope1·ation and assistance on nil occasions.

:Major Nicholson, Royal Engineers, conducted most satisfactorily, and with great energy and juclgment, all siege operations on the left bank of the Goomtec with the Dhision under Sir James Outram.

To l\Iajor A. Taylor, Commanding Bengal Engineers, I am dee11ly obliged for his invaluable serdccs and energy in the preparation of the Engineer Park, in which nothing we required was wanting, for his great energy in the arrange­ments for attacking Bnuks's House and the Begum's Palace, in which latt<.'l' operation he was unfortunately wounded, and for his most valuable assistance in all the duties of the siege.

Captain ,v. O. Lennox, Royal Engineers, conducted the columns in the attack on the Ma.rtiniere, and was acth·ely employed in securing the Begum's Palace, and in all the subsequent operations, which led to the capture of the Kaiser Bagh, and is especially and honow·ably mentioned by Colonel Harness, Royal Engineers.

Lieutenant Greathed, Bengal Engineers, was Directing Engineer in the attack on Banks's House, and subsequent operations, including the Kaiser Bagh: and was Field Engineer with General Outram's column at the attack of the 1'Ioosah Bagh, and is also especially and most honourably mentioned by Colonel Harness, Royal Engineers.

The following officers pru-ticularly distinguished themselves in the several attacks on the enemy, and have materially aided by their gallantry and intel­ligence in the reduction of the defences : - Lieutenant Beaumont, Royal Engineers, who is also most honourably mentioned by Colonel Harness, Royal Engineers; .Ensign Ogilvy, Madi·as Native Infantry, attached to the Madras Sappers, who was severely wounded at the capture of the Kaiser Ilagh; Lieute­nants l\Iedley, Hovenden, Lang, Champain, Carnegie, of the Bengal Engineers; Lieutenant \Vynne, of the Royal Engineers; also Lieutenant l\faunsell, Bengal Engineers, commanding Bengal Sappers and Miners ; Lieutenant GulliYer, Bengal Engineers, commanding Punjab Pioneers ; Lieutenant Scott, com­manding :Madras Engineers; and Lieutenant Horsford, commanding Delhi Pioneers, who have taken their share in all active duties in addition to the command of their respective corps.

To Captain Cox, Royal Engineers, Adjutant to the Royal Engineers ; to Lieutenant Humphrey, Bengal Engineers, Adjutant to the Bengal Engineers i and to Lieutenant Pemberton, Bengal Engineers, Director of the Engineer Park, my cordial acknowledgments are due for the very efficient manner in which they performed their important duties.

Lieutenant Hutchinson, Bengal Engineers, my :Major of Brigade, has been most indefatigable and zealous in the discharge of his duties, and distino-uishecl himself particularly in the caphu·e of the Iron and Stone Bridges, the Muchec Bowun, and the great Imambarah.

My thanks are also due to Lieutenant Scratchley, Royal Engineers, Lieut. H_on. A. ~raser, and Lieutenant Tulloch, Bengal Native Infantry, Assistant Field Engmeer, my Orderly Officers, who have attended me in every operation for their constant valuable services. '

---------------

ON TIIE ENOINEERINO OPERATIONS AT THE SIEGE OF LUCKNOW. 75

I bog lo briJ1g to the notice oftbc Commander-in-Chief Lieutenants Vaughan nnd Young, of the Royal Nnvy, for the courtesy and promptitude with which all my requisitions were attended to. Their guns were always to be found in the front the moment they were required. Thell' fire was directed with an accuracy which nothing could withstand.

To B1·igadier Barker, Royal Artillery, Commanding Siege Artillery; and to Colonel Maberly, Royal Artillery; and to Major Carlton, Bengal Artillery, I nm deeply indebted for their cordial assistance.

I have deeply to lament the loss of Captain Clerke, a valuable officer, and of fourteen men of the Royal Engineers, who were destroyed by an accidental explosion of gunpowder, which they were removing; also of Lieut. Brownlow, Bengal Engineers, whose gallantry and indefatigable exertions from the com­mcnccmcn.t of the siege have been most conspicuous, and gave every promise of a distinguished career.

As it is impossible, within the limits of a despatch, to mention individually every officer deserving of notice, I must commend to His Excellency's favourable consideration the valuable services of the officers whose names arc not parti­cularly mentioned, and men of the Royal and Honourable East India Company's Engineers.

It would be a great injustice were I to omit my obligation to Captain Orr and Captain "r eston, in charge of the Intelligence Department of General Outram's Force, for their -very accurate information about the enemy's works, and also to Canoge Lal and Pooran, through whom the information was pro­cw·ed.

During the operations in the city, Pooran has attended me constantly as a guide, and from his intimate acquaintance with it has been extremely useful.

I subjoin a list of the officers and men of the Engineer Brigade present at the &iege, together with a return of casualties.

I cannot conclude this report without remarking that in nine days' operations the enemy have been completely driven from a series of strongly defended positions extending over seven miles of city and suburbs ; and though they had prepared for the most desperate resistance, their opposition was crushed by the irresistible power of artillery directed against them from all quarters, for which they were not prepared.

R. NAPIER, Brigndier, Commanding Engineer Brigade.

LETTER FROM LIEUT, COLONEL H. D. HARNESS, COM. ROYAL ENGINEERS,

TO BRIGADIER R. NAPIER, BENGAL ENGINEERS, COM. ENG. BRIGADE.

Kaiser Bagh, Lucknow, 19th March, 1858. Sm, .

In compliance with your request I have to report that the siege opera-tions in which the Royal Engineers wider my command have been engaged may he considered to have commenced on the night of the 4th-5th inst., when the 4th Company and a detachment of twenty men from the 23rd Company of Roya] Engincc~·s were employed under the direction of ~bjor Nicholson, Royal

70 ON 'JUE E);lilNE.L l~lNG Ol'Ell.\l'tuXS .\'l' 'JUE SJEUC UF LUCh'.NOW.

Enginecrs1 in mnking two cniik bridges, close together, _ac1·oss the Gu~)rntce. Each ,,;-as iutcmlecl to be I 02 feet in length, and the 1·c1mnndcr of the ,nclt h of the riser was to be traYcrsed by au c1nbankment formed from the left bnnk by nnth·e labourers attached to the Force. One of' tho:,e briclgcs was complctecl by the morning of the 5th, but the number of cnsk:s ancl extent of super:-.tructurc being insufficient to span the :-;pace between the right bank and as much of the cmbn.nkmcnt ns could be complctecl during the night, only one communication couJ<l be effected, which was done by making the barrel portion about 135 feet in lcn,..,.th. During the day of the 5th, embankments of sufficient length were formed, and two bridges completed in acconlancc with the original design, by the native Snppers and Miners under their proper Officers. Cover for men and guns to protect the bridge was formed on the left bank, by a working party of the line under the direction of Captain Lennox, Royal Engineers.

On the 6th inst., the 4th Company Royal En:;iuecr.s was detached from the Enn-incer Bri,..,.acle to join Sir Jam3s Outram, who crossed the Gomntee the same da:'i~ with the 01st Dh:i;;ion. l\Iajor Nichol:son's report of the works performed by hi~ Company, while so detached, i:s forwarded herewith, and I must request your 1mrticula.r attention to the prai:sc he bestows on Lieutenant '\Vynne, Royal Engineers, for his conduct on the 14th im,-t.

On the evening of the Gth instant, in consequence of an order gfren to me by His Excellency, and re110rted to you by me, I ordered Lieutenant Harrison, Royal Engineers, to iHspcct and report upon the road between the camp of the Commander-in-Chief, near the Dilkoosha, and tha.t formc(l by Sir J amC's Outram. His report \\"US forwarded to you by me on the morning of the 7th instant.

On the ith, Captain Lennox, with the men of the Royal Engineers aYnilable for work, was employed in moving the lower of the two bridges establi.:shed on the 6th inst., about a mile lo,ver down the river, which work he completed during the afternoon, a.nd the portion of siege train attached to Sir J nmes Outram passed 0\·cr it.

On the Sth inst., the upper bridge of casks wns removed by Captain Lennox from its first position to within a short distance of the new position of the lower bridge.

On the afternoon of the 9th inst., Captain Lennox, R.E, with Lieutenants lfalcolm and Pritcha.rd, all three having been prcst:nt with the former ad­y::mce of the Cornmandcr-in Chief on Lucknow, anrl Lherefore acquainted with the l\fartiuierc, were ordered to accompany the column appointed to assault that building; and in the evening, after th1t building had been carried, and it was observed from it that the enemy had aba.ndoned a large portion of the entrench­ment in its rear, Lieutenant Beaumont was directed to attend the officer ordered to occupy the abandoned portion during the night.; and Captain Lennox remained in the i\Iartini€1·c with Gcnf'ral Lugard, by whree Division that building, and t.he entrenchment referred to, hacl been carried.

During the night of the 9th and 10th, Captain Clcrke and Lieut. Harrison, Royal Engineers, were employed with the 23rd. Company and a large party of natives, in moving the upper bl'idge of casks from the place down the stream to which it had been moved on the 8th instant., to that pa.rt of the river on which the enemy had closed the left of the entrenchment taken by us the preceding . evening.

0~ -r1rn E~til:-i'LEHI:,;'0 Ol'Elt.\fllJ.;'iS .\.'f 'fllE SIELiE OF LUCKNOW. 77

On the 11th inst., Major Nicholson having- reported that Lieut. Swctenhnm had bel'll wouru.kd, nnd that he much needed another officer, Lieut. 1\lalcolm was dctaC'hcd to his nssi~tancc.

The same day, being ordered lo repair the bridge across the canal ncarllanks's House, Capta in Clcrke, Royal Engiacers, was directed to execute that serdce, nssi'\ted by Lieutenant Pritdmrd, Hoyal Engineers. The space to be spanned was 36 fo~t in width, and twenty-one hours were occupied in repail'ing it by about fifty men of the 23rcl Company. In the afternoon of this day the garden wull of the Bcgum':5 Pabec, the entrenchment in front of it, and tho serai on the opposite side of the road, having been breached by guns in battery ll('ar Banks's House, and the intention to assault by three columns having been communic,~ti:d ti> me, I requested you to permit me to detail an officer for one of the columns of nssa.ult1 which being assented to, I named Captain Cox, Roynl l:nginccr:;, nnd it ·was arranged, in order that he might not supersede the subaltern officers already appointed to the columns, that he shoul<l accompany the column to which Major Taylor, who was to be the Directing Engineer of the nssault, intended to attach him:;df.

Thi:; was done, but ~Injm· Taylor being unfortunately wounded during the opcmtiou, Captain Cox be:cn.me the senior officer with the party within the captured premises, and was, as such1 placed by me in communication with the Brigadier commanding the troops by which the assault was effectl'cl.

During the evening I received au order from you to remain in the captured buildings, and since that period I retained, by your desire, the principal dircc~ tion of the operations which terminated in the capture of the Kaiser Bagh on the 16th inst. During the night of the 11 th-12th, the obstacles to a free com­munication within the premises of the Begum's Palace and with the public roads were removed, and an epaulment thrown up to protect a communication across the road, between the palace and the scrai, and to serve also as a parapet to two guns to oppose the enemy's works which enfiladed the road. And during the day of the 12th, two openings were effected through the wall separating the Begum's property from Jaffir Ali':;, whose house was then occupied without re­sistance; and a small semi, in advance of tha.t captured on the preceding evening, was also occupied without resistance, together with a mosque contiguous to and overlooking it. Some 8-inch morta1·s were moved into the small advanced serni, and some placed in rear of it, also some JO-inch mortars in the larger but more retired serni, with directions to shell that pn:rt of the city immediately in our front, extending to and including the Kaiser Ilagh.

In the night of the 12th-13th, an openingwos made through the wall between Jaffi.r Ali's and Jcrar-o-Dowlah's premises; and in the morning the latter were occupied without resistance. But as it was found at dnylight that the musquctry of the Irnambarah could bear on the opening that had been made iu the front wall of Jaffir Ali's property, a new opening was made through it into a row of sl1cds at right angles to it, by the destruction of the cross walls of ,vhich a perfectly covered route for the guns was obtained: they were JJlaced in battery that afternoon within about 70 yards of the wall of the outer court of the Imam­barah1 and had completely brcach~d the outer walls and partially brl!achccl the iuuc·r wall before dark, one S-inch gun a.ml one 2-!-pountlcr being employed fol'

the purposl'.

j8 ON TllE ENGINEERING OPERATION~ AT TllE SIEGE OF U JCKNOW,

During the night of the 13th.14th, the outer breach was e:,mmined and fon_nd to be very easy of ascent; it wns also intended to hnve examined n trench which it was obscned the enemy had formed across the rond 011 our left, to flank the outer wall of the Imnmbsrnh, but the enemy discovered the attempt and wounded the Sikh soldier, who, together with one of the Sikh officers, was accompanying the Engineer Officer. Fire was maintained upon the breach during the night1

every two discharges of round shot being followed by a shcl1 nnd a round of grope; and at daylight the breaches were considered 210 far advanced that arrangements were made for the assault.

A party of 100 Sikhs were to form the storming party, and to be followed by the native Sappers with powder bags under Lieutenant Brownlow, of the Bengal Engineers, and 32 men of the 23rd Company under Captain Clerke, Roya.I Engineers, with scaling ladders and crow bars, axes, &c., these to be followed by 200 Infantry, after whom were to advance 50 native Sapper~ with ladders and tools, under Lieutenants Medley and Lang, and a native working party under Lieutenants Scott, Fraser, and Burton, with tools and matedals for any cover or entrenchment that might be found necessary; and the whole of Brigadier Russell's Brigade was to be retained in readiness to support tho assault.

It had been obserYed that between the trench, which the enemy had made across the road, and the breach, there was a door in the outer wall of the Imam 4

barnh, and it was reported that there was a corresponding door opposite to it which would lead into the principal building. Arrangements were therefore made for a party of 25 men to advance against the trench, followed by the offi.cer, with powder bags to blow in this outer door, at the same time that the storming party moved forward; and Lieutenant Brownlow was directed, on passing the first breach, to hu·n to his left, and blow in the opposite door, if he found one.

Lieutenant Beaumont, Royal Engineers, was ordered by me to be prepared to blow in the out~r door, and his attention being thus directed to that part of the enemy's works, he found reason to believe that the trench on our left was in connection with a house on our side of the road between our front and the Imambarah, and that if manned when we proceeded to the assault, it would be from that house. He the1·efore asked permission to be allowed to work his way through the few earthen walls between us and the house referred to, and with the aid of Major Brasyer and a few of his men, to blow in the wall of the house and expel the enemy. This permission was given to him by me with the approval of Brigadier Russell, oll the understanding that he would return and report the result, or if his proceedings were not complete before the breach was, that I should recall him to ca1Ty out the original plan of blowing in the door. He succeeded in driving the enemy from the house, and then proceeded to blow in the outer wall of the Imambaratl, which being successfully executed, the Sikhs with him rushed in at the moment that the storming party had been ordered to their arms.

The unexpected entry of the Sikhs through the opening made by Lieutenant Beaumont checked resistance, and the assaulting columns passed the breaches

ON THE ENGINEERING OPERATIONS AT TIIE SIEGE OF LUCKNOW. 79

without difficulty, and were able to seize, as rapidly as openings could be made for them, the enclosure of the King's Coachman's, nnd King's Brother's houses, The roofs of the latter, looking down on the Kaiser Bagh, offered a good position for our new front, and having succeeded in collecting about 100 men in each of the two buildings which compose the King's Brotb.er's residence, I recommended Brigadier Russell to stop the further advance, and obtain firm possession of the ground we hnd passed over. The Sikh Regiment, however, persisted in pressing forward, and made their way into the courts of the Kaiser Bagh, fol­lowed by many of the troops who had taken part in the advance. As soon as practicable, therefore, an opening was formed from the Chena Bazar into the court whern the two large tombs are situated (the place recommended by Mr. Kavanagh, whose local knowledge at this moment was ,•aluable), and small detachments of men who had not lost their order were placed in commanding buildings, ,iz., in the larger tomb, one of the detached buildings in the principal court, and the gateway in the centre of the norlh-,~est side of that court. Soon after a party of about sixty men of the 10th Regiment was marched round the great square in order, halting occasionally as they passed the south-east and south-west sides, from which some fire was maintained by the enemy, and sending a section in to search the buildings. At two or more points large numbers were seen by the parties thus sent ll1, endeavouring to escape; and in these instances more were sent in and ordered to fire from the roofs. No doubt many of the eneruy were thus killed.

During the afternoon and evening, as troops came up, they were quartered in the buildings, and the return of the enemy in force was prevented by their presence, though cnsualties continued to occur until late.

Much gunpowder was found by the men who searched the buildings, and Lieutenant Beaumont, who accompanied the party, was employed in destroying such portions as appeared most in danger from the fires then burning in thrc<' parts of the square.

On the 15th inst., the whole day, and all the available working men were employed ll1 merely checking fires, and in destroying gunpowder.

I have thus related, to the best of my recollection1,the events which took place under my notice from the 4th to the 15th inst., and have only to report to you that e,'ery officer under my command, whose name I have mentioned in this report, conducted himself with zeal and intelligence, and that all deserve your approbation.

But I must pal'iicularly record the ,·ery high opinion which these operations have enabled me to form of Captain Lennox, Royal Engineers, and Lieutenant Grcathed, Bengal Engineers.

I must also praise most highly the intelligence and zeal of Lieutenant Beaumont, Royal Engineers, though I do not approve of his having blown in the outer wall of the lmambarah before he had reported progress and obtained instructions.

I annex the report addressed to me by Lieutenant Greathed of the pro­ceedings adopted for the occupation of the Tarn Kotee on the 14th instant,

MBIOR . .\.ND.\ REL.-\TJ~O TO TllE SIEGE OF LrCKNO\V I:-l' l\IAncn, 18,;8, l\I0!m

ESPECIALLY WITII REFERENCE 'l'O 'l'llE DISTRJDU'l'[ON OF TIii~ Jl0Y . .\.L

ENGINEERS DURING 'fllE OrER.\..l'IO:SS. Co:;UPILED IN l SGO, FROM

NOTES OF 1JIFFEREN1' OFFICEilS1 DY LIEU'!'. COLONEL LENNOX, R,E.

~nd l\larch.-Thc Siege of Lucknow may be con~idercd to have commenced on the 2nd ~larch, 1838, when the Commander-in-Chief ad,·anced from JJunt:1ra anti marching through the camp at the Alumbagh, gained poss0ssion, with trifling loss, of the buildings of the Dilkoosha, and encamped on the east side of the city in the Dilkoosha Park, which touches the right bank of the Iliver Goomtce.

3rd ~Jarch.-On the morning of the 3rd :i\farch the Engineer Brigade and some more of the Force joined the Commander in-Chief from the Alumbag-h, where, howe\'er, some troops were still left. The Engineer Brigade and Park were established in the gardens at Bibiaporc, where the Comman<lcr-in-Chid subsequently fixed hii:; head-quarters.

During the day some Native Sappers threw up a breast-work for two guns in front oft.he Dilkoosha llouse: Lieutenant Pritchard, R.E., and 30 men of the 23rd Company, Royal Engineers, during the night extended this work into a. Battery (No. 1, L) , for four guns to keep down the fire of the enemy's batteries in their first 1ine of works, and to check that of two or three guns which they had advanced to the northern angle of the 1'fartinit!re. Strong picquets were posted in the garden of the Dilkoosha and in the l\Iahomed Bagh•.

A ford across the Goomtee was staked out; and some Delhi Pioneers were employed in preparing the banks of the river for the formation of bridges of casks: these parties were protected by a co..-ering party of the 4th Company, Royal Engineers.

4th March. -On tbo 4th 1\Iarch a force under !\fojor General Franks joined: this force, which consisted of Her Majesty's 10th, 20th, and 97th Regiments, five battalions of Goorkas, and some artillery, had marched towards Lucknow from the south-east.

At sunset two barrel-pier bridges were commenced under the direction of l\Iajor Nicholson, Royal Engineers; the party employed consisted of Lieutenants ,vynne and Swetenham, four sergeants and 106 men, Royal Engineers; and Lieutenants Tennant and Smyth, Bengal Engineers, with 120 Native Sappers. Each bridge was intended to be 102 feet in length, and the remainder of the width of the ri\'er wn.s to be traversed by embankments extending from the left bank. One communication was effected during the night, by using 135 feet of banel piers for its bridge. C£Lptain Lennox, R.E., was Directing Engineer at the Dilkoosha House; Lieutenant Pritchard, 1 sergeant, and 33 men of the 23rd Compa,ny, Royal Engineers, were employed in improving the battery (No. 1, L ), in front of the Dilkoosha House during the first portion of the night, and subsequently they were sent to reinforce the party making the bridges.

5th March.-Early in the morning of the 5th March the enemy brought out a horse battery to annoy the working party at the bridges, but it was soon driven off by the two guns with the covering party.

• An encloimrr 1,400 yards to the south ofilanks's Uou~c.

ON TRE ENGINEERING OllERATIONB AT THE SIEGE OJI LUCKNOW, 811

During the day the causeways were continued from the left bank, and both the bridges were completed in nccorda.nce with the original design : a party of 1 sergeant and 10 men, Royal Engineere, remained on duty at them to keep them in order.

A tete-dc .. pont, a battery for four guns on some mounds to the north-west of the bridge, cmd nn infantry trench, to connect the battery with the tete•de~ pont, were thrown up on the left b:rnk of the Goomtee, under the direction of C.1ptain Lennox, Royal Engineers, by a working party of 200 men of Her lllojesty's 63rd Regiment; Lieutenant Keith and 11 men of the 4th Company. Royal Engineers (relieved at 10 P.M. by a similar party of the 23rd Company under Lieutenant Malcolm, R.E.), were employed on these works, which were finished during the night.

Lieutenant Harrison, R.E., 1 corporal and 8 Sappers of the 23rd Company, Royal Engineers, constructed a shot-proof parapet on the advanced tower of the Mahomed Bagh this evening.

6th 1\Iarch.-At 2 A.M., on the 6th l\Iarch, a force of about 7,000 of all arms, under 1\Iajor General Sir James Outram, G.C.B., commenced crossing the Goomtee by the two barrel bridges: it consisted of the 3rd Infantry Division, 14 Squadrons, 3 Troops of Horse Artillery, 2 :Field Batteries, the 4th Company of Royal Engineers, with Lieutenants ,vynne, Swetenham, and Keith, Royal Engineers, Lieutenant ,vatson, Bengal Engineers, and 200 of the 15th Punjaub Native Infantry (Pioneers) under Lieutenant Hovenden, Bengal Engineers, and Ensign Nuthall: the Engineer force was under the command of l\Iojor Nicholson,. Royal Engineers, who conducted all the Biege operations on the left bank of the Goomtee.

Sir James Outram, after crossing the ri'\'"er, inclined slightly to the eastward, and clearing the country and villages as he proceeded, he established his camp, on the great road from Fyzabad to Luck now: strong picquets were posted to keep up the communication between the two camps. Lieutenant Harrison, Royal Engineers, was sent to im;pect and report on the road with a view to the movement of the heavy artillery.

Captain Lennox, Royal Engineers, with 2 sergeants nnd 63 men of the 23rd Company, Royal Engineers, dismautled the lower bridge during the night, preparatory to removing it lower down the river to a Bpot where it could not bEJ seen by the enemy occupying the l\lartinif!re.

7th l\larch.-The enemy made an attack upon Sir James Outram's position this morning, but was repulsed.

The lower bridge was moved down stream to a point near Bibiapore, where the bridge was again formed by a party under Captain Lennox, Royal Engineers.

Lieutenant Swctenham, Royal Engineers, "ith 20 men of 4th Compa11y Royal Engineer,, and 60 Muzbee Sappers, prepared the road for the heavy artillery between the two camps, as point~d out by Lieutenant Harrison, Royal Engineers. The siege train for the operations on the left bank crossed the river this evening by the lower bridge and joined Mojor General Outrnm's cnmp.

8th March.-On the 8th a party of 1 sergeant and 32 men, Royal Engineere1

under Captain Lennox, U.E., rnoveJ. the uppel' barrel bridge lower down the river.

L

82 ON 'l'IIB BNOIKBERINO OPERATIONS AT TIIE SIEGE OF LUCKNOW,

A party of Native Se.ppers under Lieutenant n.,vard, Bengal Engineers, mad_e a battery (No. 2, L) near the Dilkoosha Park for six guns, to bear on the Marti•

nit!re. A battery (No. 3, L), for four guns, was also thrown up on the right front of

the Mohamed Bagh, to fire on the Martiniere, by Lieutenant Fulford, Bengal Engineers, and a party of l\'I uzbee Sappers.

On the right attnck during the night a battery for 10 guns en barbetto (No. 1, R) was constructed at the Kokral Bridge to command the enemy's posi­tion near the Race Stand.

9th l\Iarch.-A heavy fire was kept up from all the batteries including those made last night.

Sir James Outram stormed the Race Stand, and carrying all before him, occupied the whole of the left bank of the river as far a, the Badshah Bagh and the Hazari Bagh. Ho immediately established a battery (No. 2, R) of 12 guns, no artificial cover being required, to enfilade the enemy's first line of works.

A battery for 4 guns, was thrown up to the east of the Race Stand at)/, to fire on the Shah Nujjif and the Motee Mahal.

Lieutenant Beaumont, Royal Engineers, was Directing Engineer at the Dil­koosha Park this morning. Two guns of the Naval Brigade were placed under natural cover in advance of the Dilkoosha at z, to fil'e on the MartiniE!re in flank and reverse.

About 2 P.M., after a heavy cannonade, the MartiniE!re was taken with little resistance by Hope's Brigade. Captain Lennox, Royal Engineers, was the DirPcting Engineer in this attack, and remained on duty with Major General Lugard's Division that night; the following parties were with the columns : Lieutenants Malcolm and Pritchard, Royal Engineers, 2 corporals, and 6 men of the 23rd Company, Royal Engineers; Lieutenants Lang, Forbes, and Thack­eray, Bengal Engineers, with 200 Muzbee Sappers. Communications were immediately made across the numerous trenches that had been dug by the rebels around the MartiniCre: the outer wall of the MartiniCre Garden ,vas loop­holed; the village to the north-west of the Martiniere was occupied and pre­pared for defence, as also was the village of Jea Mhow, on the other side of the canal, the banks of which at that spot are sloping. Late in the evening the 42nd Highlanders and ,vyld's Sdks advanced and occupied a part of the enemy's first line, which bad been evacuated on account of the enfilade fire from the guns on the right attack. Lieutenant Beaumont, Royal Engineers, was directed to remain with the force occupying the left, and Lieutenant Thackeray, Bengal Engineers, with that occupying the right of the abandoned line: these officers loopholed buildings where necessary, and otherwise secured the advanced position, which extended from the river nearly up to the bridn-e on the Marti• niere Road. ~ieuten~nt Lang, Bengal Engineers, with 200 K1uzbee Sappers, was employed 10 makmg a road through the first line of works: he was relieved at 11 P.M., by Lieutenant Iudge, Bengal Engineers, and Ensign Nuthall with 100 Muzbee Sappers and 200 Delhi Pioneers.

Th~ upper bridge of casks_ was moved up entire to a point above the enemy'• fi~st hne of works b! Captam A. J. Cl~rke, R.E, Lieutenant R. Harrison, R.E., Lieutenant Champam, B.E., and ~ns1gn E.?· Garstin, 29th Native Infantry, and a _strong b~dy of Royal Engineers, Native Sappers, and Pioneers. Thia operation occupied 17 houro, and was completed by 7 A,M:, on the 10th March.

ON 'tHE ENGINEERING OPERATIONS AT THE SIEGE OF LUCXNOW. 83

10th Mnrch.-At daylight two horse artillery guns joined the left advanced party, moving in by the road made during the night.

Early this day a battery (No. 4, L ) for four guns, one howitzer, three 8-inch mortars, and some rockets, was established at the end of tho ~1artiniere Park: advantage was taken of some natural cover, and the guns were soon playing upon Banks's House, the garden wnll of which was breached early, when it was taken by the 42nd and ,vyld's Seiks, who also gained possession of the houses on the other side of the road as far as No. 3, D Bungalow. Lieutenant Greathed, B.E., was the Directing Engineer in this attack; Lieutenants Beaumont, R.E., and Brownlow, B.E., accompanied the storming parties. The Karabola was also occupied about the same time. Thus on the morning of the 10th March the enemy's first and most formidable line of works had been completely taken.

Natural cover on the right of Banks's House was converted into a battery (No. 5, L) for four guns and eight mortars to shell and breach the Begum's Palace. Places were also prepared among the D Bungalows for two 8-inch naval guns (Battery No. 7, L) to batter the bastion in front of the Huzrut Uunj and for six 54-inch mortars (Battery No. 8, L ).

Communications were at the same time made between Banks's House and the D Bungalows, and also to the rear.

These batteries (under Lieutenants Greathed and E. Brownlow, B.E.,) and communications (under Lieutenant Gulliver, B.E.,) were very expeditiously made under the superintendence of Captain A. Taylor, B.E., and the guns were brought across the ditch and opened fire soon after Banks's House was in our possession.

On the 1·ight attack the following works were made ucder the superintendence of Major Nicholson, Royal Engineers.

A battery (No. 3, R), for four 24-pdrs., two 8-inch howitzers, and five 8-inch mortars, was formed on the left of the Badsbah Bagh to counterbatter the bat,. teries between it and the Kaiser Bagh, and to fire on the palace itself: this battery opened fire during the day.

Roadways were made through the Badshah Bagh. The Dilaram House was seized, and fortified, under a heavy fire from the

Chutter Munzil, by a party under Lieutenant ,vynne, Royal Engineers. During the night a battery (No. 4, R), for four 24-pdrs., two 8-inch howitzers,

and five mortars, was thrown up in front of the Badshah Bagh to fire on the Kaiser Bagh : this battery opened fire on the morning of the 11 th.

11 th March.-Captain Clerke, Royal Engineers, with Lieutenant Pritchard, 3 sergeants, and 48 men of the 23rd Company, Royal Engineers, was employed in repairing the bridge across the canal near Banks's House.

The European Barracks1 the Secundra Bagh, the Kuddum Russoo1, and the Shah Nujjif were taken possession of this morning by parties conducted by Lieutenants Medley, Lang, and Carnegie, Bengal Engineers. The enemy were just about to occupy t.he Secundra Bagh when our troops moved up.

Two 8-inch naval guns were put in position (at No. 9, L), in rear of the garden wall of No. 3, D bungalow: these guns were intended to breach the wall of the loopholed serai on the opposite side of the road to the Begum's Kotee, which they succeeded in doing through two kutcha garden waUs which intervened.

The Rre from the batteries had been kept up all night, and had made two practicable breaches in the compound wall of the Begum's Palace, and in the entrenchment and palisade defences in front of it. The assault was given at

'8! ON TUE ESGINEERINO OPBRA'l'10N:3 A'f 'l'llE SU:OE 01? LUCKNOW.

3! P,M. by three columns, two against the Begum's Palace, ~nd one against the loopholed serai opposite to it. Captain Taylor, llcngal Engmeers, who had the general arrangement of the attack, accompanied the left column, to which Captain Cox, R.E., Lieutenant Scrntchley, H.E., and Lieutenant Smyth, B.E., were attached, and Lieutenants l\Iaunsell, B.E., and Scott, M.E., lt:d the two other columns. Parties of Uoynl Engineers and Nathe Sappers with JJowdcr bags nod ladders, &c., were attached to them: the assaulting columns were furnished by Hope's brigade of L11gard's division, and Brigadier Napier, attended by Colonel Harness, Commanding Royal Engineer, nncl Captain Lennox, R.E., accom• panied the column: the assault was successful; in it 4 officers, and 60 or 70 men were killed and wounded, many of them by men who barricaded themselves in the dark rooms around the courts, where they could not be got at except by making holes in the roofs or blowing in the doors. Captain Taylor, Bengal Engineers, having been unfortunately wouncled, the securing of the position devolved on Captain Cox, R.E. Later in the evening Colonel Harness, Com• mantling Hoyal Engineer, received orders to remain in the captured premises, nnd to take the principal direction of further operations. The works carried on during that night were-removing the obstacles to a free communication within the premises of the Begum's Palace and with the public road i and throwing up an epaulment to protect the communication across the road, and also to serve as a parnpet for two guns (No. 10, L), to fire at the enemy's bastion in the second line, which enfiladed the road.

This afternoon, ~foharajah Jung- Bahadoor arrh,ed with a large force of Goorkas, and was sent round to the south side of the city: Lieutenant Sankey, l\Iadras Engineers, was the engineer officer with His Highness's force.

Lieutenant Malcolm, R.E., was transferred to the right attack to replace Lieutenant Swetenbam, R.E. 1 who had been wounded.

Lieutenant Harrison, Royal Engineers, was sent this day to ,•isit the right attack, ancl to ascertain the movements going on there. General Outram, having shifted his camp to a position close to the Race Bungalow, advanced with two columns against the northern suburbs: the first column made a great detour, surprised and cut up a large body of the enemy's cavalry, took two guns and reached the stone bridge; but the General, fincling the extent of ground too great for his force, fired that part of the suburbs, and contented himself with holding the position round the iron bridge, which had been taken by the second column. His loss was about 8 officers and 40 men killed and wounded.

A battery (No. 5, R), for two 24-pdrs. was immediately commenced on the north side of the iron bridge: it was completed during the night by a party under Lieutenant Malcolm, Royal Engineers; its object was to subdue the enemy's fire from the opposite side of the bridge and to command the stone bridge.

12th March.-On the right attack during daylight on the 12th March two batteries were thrown up under Major Nicholson's orders.

Battery No. 6, R, for four 8-inch guns, to fire on the Residency and also 00

the buildings extending from thence to the Kaiser Bagh, was constructed on the 1·ight front of the Badshah Bagh.

Battery No. 7, R, for two 2-l-pdr. guns, was on the l~ft of the iron bridge, and intended to subdue the fire from the opposite bank of the river.

On the left attack Captain Clerke, Royal Engineers, completed the repair of the bridge across the canal, which was commenced yesterday t with .the as.sis ta.nee

'ON TOE ENOlNEP.:Rll\G OPERATIONS AT THE SIEGE OF LUCKNOW. 85

0: Lieutenants Pritchard nnd Harrison, 3 serge-ants, and 48 mPn Royal En­gineers: this service occupied 21 hours, the space to be spanned being 36 feet.

Under the direction of Colonel Harness, Commanding Royal Engineer, the nd,·ancc was carried stenclily on: two openings were effected through the wall Sf'parating the Begum's property from an adjacent mosque and Jaffer Ali's house, wllich were both occupied without resistance. A small serai on the other side of the Huzrut Gunj Road, in advance of the loopholed one captured on the previ~us evening, was also occupied. without resistance, together with a mosque contiguous to and overlooking it. Four 8-inch mortars were moved into the advanced serni, and two 8-inch mortars, were placed in position in its i·car; also five 10-inch mortars were moved into the loopholed serai taken on the 11th. The fire from nil was directed on the Imambarah and the buildings between it and the Kaiser Bagh. The communications with the rear were also improV'cd.

When a hole had been made through the wall between Jaffir Ali's and Jerar­o-Dow]ah's gardens, the enemy opened a smart musketry fire on it, a gun was therefore brought up, and replied with grape, but the gun was withdrawn after some casualties had occurred, as it pre·vented the Sappers continuing to enlarge the opening, which was through solid masonry. Lieut. Harrison, R.E., was with the working party of that corps that day.

The mmal mode of pushing forward the advance, after the capture by assault of the Begum's Kotce, was as follows :-a heavy fire of shells was kept up on the buildings to be attacked, while the Engineers were employed in forming openings through the walls: holes were at first made by blasts in the walls, or by charges under them; these charges were small for fear of bringing down the upper parts of the walls, the removal of the rubbish from which would have caused additional labour and loss of time. ,vhen once holes were made through the walls, they were enlarged into practicable openings by means of crowbars, pickaxes, &c. Small parties were then moved through and secured the newly gained ground. The windows of the prominent adjacent buildings were provided with sand-bags, and the parapets and other walls loopholed; nnd from these positions our riflemen kept down the fire of the enemy.

13th l\Iarch.-At day-break on the 13th, possession was taken of Jerar-o­Dowlah's house and compound, and a battery (No. 13, L), was formed behind its advanced wall: this batterv was intended to breach the little lmambarah, the outer wall of which was ,viihin 70 yards of it. Lieutenant Gulliver, B.E., was engaged in the construction of this battery.

As a great portion of Jerar-o-Dowlah's compound, and also the opening made into it last night from Jaffir Ali's compound, coulcl be seen from the little Imam­barah, a new opening was made on the right, under cover of Jerar-o-Dowlah's house, and also one on the left into a row of sheds running towards the Imam­barah, by the destruction of the cross walls of which a perfectly covered route for the guns was obtained. One 8-inch gun and one 24-pdr. were brought up and placed in the battery by noon, and they had breached the outer wall com­pletely, and the inner wall partially, before dark.

Colonel Harness, Commanding Royal Engineer, examined the outer breach and found it to be easy of ascent: he also proceeded, accompanied by Lieutenant Da Costa and one of his Seikhs, to examine a trench which the enemy had formed across the road on our left, to flank the outer wall of the lmambnrah, but wrts discovered by the enemy, who wounded the Scikh soldier in attendance.

86 ON 'l'HE ENGINEERING OPERATIONS AT THE SIEGE OF LUCKNOW.

Openings were made through the front wall of Jerar-o-Dowlnh's compound to the right and left of the battery (No. 13, L), and the buildings were taken possession of as for as the rond next to the Imnmbarah. A battery (No. 14, L), was also made this nio-ht for two guns to breach o. white serai on the right of the Huzrut Gunj Road: and for five mortars to shell the city in our front.

During this night Lieutenant Harrison, 3 sergeants, and 42 men, Royal Engineers, were employed at the upper bridge of casks.

On the right attack four 8-inch mortars were added to the amount on the riaht front of the Badsbah Bagb. These batteries and the mortars on the left atlack kept up during the night a hea,,y fire of shells on the little Imambnrab, the Kaiser Bagh, and all the buildings between them. :Fire was also maintai~ed on the breach in the Imam barah, every two discharges of round shot being followed by a shell and a round of grape.

14th Mnrch.-At daylight on the 14th the breaches were considered so far advanced that the following arrangements were made for the assault: the storming party to consist of 100 Seikhs, to be followed by native Sappers with powder bags, under Lieutenant. Brownlow, B.E., and 32 men under Captain Cle1·ke, R.E., with scaling ladders, crow.bars, axes, &c.: these to be followed by 200 Infantry, after whom 50 nath·e Sappers were to advance with ladders and tools, under Lieutenants Medley and Lang, B.E., and a working party of natives under Lieutenants Scott, Fraser, and Burton, M.E., with tools and materials for any cover or entrenchment that might be found necessary. 'fhe whole of Brigadier Russell's Brigade of General Franks's Division was to support the assault.

While these parties were being formed up, Lieutenant Beaumont, R.E., worked from the left of the advanced post through a few earthen walls to a house on our side of the road between our front and the Imambarah: he was accompanied by Major Brazyer and some of his Seikhs, and succeeded in blowing in the wall and driving the enemy out of the house, which proved to be in connection with the trench intended to flank the outer wall of the Imambarah. Re next blew in the outer wall of the Imambarah, and the Seikhs who were with him rushed in: this unexpected entry checked resistance, and the assaulting column passed the breaches without difficulty at 9 A.M., and were able to seize, as rapidly as openings could be mado for them, the enclosures of the King's Coachman's and the King's Brother's houses, which o~erlooked the Kaiser Dagh.

Here it was considered advisable to stop and obtain secure possession of the ground that had been passed over, but Brazyer's Seikhs persisted in pressing forward, and made their way into the court of the Kaiser Bagh on the left, followed by many of the troops who had taken part in the advance: as soon as practicable therefore an opening was made from the Chena Bazaar into the court in which Saadut Ali's tomb stands. Small detachments of troops were placed in the commanding buildings, viz., the tomb, the building at the north corner of the Kaiser Bagh, the gateway on the north western side, and a detached building in the centre of the grand court.

Colonel Harness, R. E., shortly afterwards marched a party of 60 men of the 10th Regiment round the grand square1 who systematically cleared the buildings: much gunpowder was found, and Lieutenant Beaumont, R.E., who accompanied the colonel, destroyed such portions of it as were most in danger from the fires then burning in three parts of the oquorc.

02'! THE ENGINEERING OP£RATIONS AT THE SIEGE OF LUCXNOW. 87

The Engineer Officers employed in these operations were Colonel Harness, Commanding Royal Engineer, Captains Cox., Clerke, and Lennox, R.E., Lieut, Oreathed, B.E., Lieutenant Beaumont, R.E., Lieutenant Lang, B.E., Lieutenant Brownlow, B.E., Lieutenant .Medley, B.E., Ensign Ogilvy, attached to Madras Sappers (severely wounded); 3 men of the 23rd Company, Royal Engineers, were also wounded.

In the mean time the Mess House and the Motee Mahal were occupied by troops moved up from the European Barracks and the Seoundra Bngh, and more troops coming up prevented the return of the enemy to the Kaiser Dngh in force, though casualties continued to occur.

Lieutenant Pritchard, R.E., was employed at the Secundre. Bagh, and Lieut. Harrison, R.E. in breaking up the upper bridge of casks and moving it up stream.

On the right attack a breast-work was thrown up by Lieutenant Wynne and a party of the 4th Company, R. E., on the Iron Bridge. Previously to the assault on the Imambarah the batteries directed their fire on the buildings between it and the Kaiser Bagh, but afterwards this fire was turned on the Residency and other buildings in advance of the Chutter Munzil.

15th llfarch.-On the 15th, the whole of the Kaiser Bagh was secured, and also all the principal buildings up to the Chutter Munzil.

Battery No. 161 L, for six 54-inch mortars, was establiehed in the north-west court of the Kaiser Bagh to play on the city.

Lnrge parties were employed in improving the communications between the different posts and with the rear, in checking fires, and in destroying the enormous quantities of gunpowder which were found in all directions. The 23rd Company, Royal Engineers, took up its quarters in the Zenana at the Kaiser Bagh.

Lieutenants Beaumont, Pritchard, and Keith, with 100 Royal Engineerst constructed a bnrrel-pier-bridge near the Secundra Bagb.

Lieut. ,vynne, 1 sergeant, and 9 men of the 4th Company, Royal Engineers, removed the breast-work from the Iron Bridge: this was n service of much danger, and the conduct of the party was highly praised by Major Nicholson, R.E.

16th March.-Douglas's Brigade was moved across from the lt::ft bank by the bridge of casks at the Secundra Bagh, and attacked and drove the enemy from the Painted House, the Residency, and the Iron Bridge: and later in the day seized the l\Iuchee Bawun, the Stone Bridge, and the Great Imambarah. These operations were directed by Brigadier Napier B.E., the Engineer Officers em­ployed being Lieutenant Hutchinson, B.E., Lieutenant Scratchley, R.E., J,ieut. Brownlow, B.E., Lieutenant Cbampnin, B.E., Lieutenant Smyth, B.E., Ensigns Nuthall and Knowles and Mr. May, C.E. Major General Hope Grant, with the Cavalry division on the north, and Brigadier Campbell, with the Cavalry from the Alum Bagh, pressed out to intercept the fugitives, and the Goorkas attacked the native city on the south.

Fh-e 8-inch mortars were immediately placed in position in the Great Imam­barah: two naval guns and five 10-inch mortars were also posted in the Residency, and the whole kept up a steady fire upon the city during the ni~ht.

Colonel Harness, Commanding Royal Engineer, advanced from the Kaiser Bagh with a portion of the 97th Regiment and took possession of Philip•'.• H_ouse and l\lumtaj-o•Dowlah'a. Large parties were employed on the commumcabom,, deetroying po1vder, and putting out fires.

88 OIi THE ENGINEERING OPEUTIONS AT TllE SIEGE OF LUCKNOW,

17th i\Inrch.-On the morning of the 17th, Colonel Ilnrnesl!I, Commanding Royal Engineer, accompanied by Captains Cox and Lennox, proceeded with the 97th Regiment, 30 men uf the 23rd Company, Royal Engi11eers, under Lieut. Hnrrison1 R.E. 1 nnd 60 Pioneers, under Lieutenant Scott, M.E., to open up the Cawnpore Road, from the Kaiser Bngh, while three Regiments of Goorkas, nccompnnied by Lieutenant Sankey, 1\I.E., nud Lieutenant Murray, B.E., advanced from Alum Bngh by the same road: these columns did not meet with o.ny resistance. The principal houses were occupied, the Char Bngh Bridge was repaired by Lieutenant Sankey, M.E., and the obstructions on the road were removed by the Eugineers.

In the mean time Brigadier Napier, B.E., had conducted a portion of the 3rd Infantry Division, accompanied by Captain Clerke, Lieutenant Pritchard, and 30 men of the 23rd Company, Royul Engineers, and Lieutenants Brownlow n11d Lang, B.E., from the Great Imambarah to clenr the city in that direction. In one of the streets the enemy had left some carts containing about three tons of gunpowder: the Engineers were engaged in remo,·ing this powder and throwing it down a well, when from some unexplained cause it exploded. Captain Clerke, R.E., Lieutenant Brownlow, B.E., and 14 men of the 23rd Company, Royal Engineers, died from the effects of this explosion, ns also about 50 men belonging to other Corps.

Lieutenant Harrison, R.E., commenced a sketch of the enemy's lines, The 4th Company, Royal Engineers, under l\Iajor Nicholson, came in and

encamped at the King's Brother's House, Kaiser Bogh. 18th 1\hrch.-On the J 8th l\Inrch a mine was discovered under the Stone

Bridge: it was untampecl: the gallery was 60 feet long and the charge consisted of 1,400 lbs. of powder which was removed and destroyed.

The officers and men of the Engirieers who were blown up yesterday were buried at 2 P.M. in the garden x near the small mosque of the Kaiser Bagh.

'l'he communications were improved and more of the city was occupied during the day.

19th March.-On the 19th, Lieutenant Keith and 50 men of the4th Company, Royal Engineers, dismantled the lower bridge of casks and returned it to the park.

Major General Outram attacked and took the }.foosa Bagh; he pursued and cut up between 400 and 600 of the eni:my and took 12 guns. Major Nicholson, R.E., Lieutenant Greathed, B.E., and some of the 4th Company, Royal Engineers, accompanied his force. Brigadier Campbell had been ordered to intercept fugiti,,es with the cavalry from the south of the city.

20th March.-On the 20th the Moul vie returned with a body of men and took u~ a position in the city, from w~ich he was however rlriven by a party of Highlanders on the 21st, from which day the whole city may be considered to have been in our possession.

21st March.-During this time large parties were employed under the En­ginee:s in fortifying a~1d prep~riug accommodation in the buildings about to ba occupied as barracks, m levelling those portions of the town which interfered with their defence, in making roads through the heart of the city, and io constructing military posts at the two bridges ns described in Paper V of the 9th volume of the Professional Papers.

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PAPER XI.

REPORT TO THE SECRETARY OF STATE FOR ,VAR ON THE RESULT OF

INYESTIGATIONS CONDUCTED AT ,VOOLWICH AND CHATHAM ON THE

APPLICATION OF ELECTRICITY FROM DIFFERENT SOURCES TO THE

EXPLOSION OF GUNPOWDER.

BY C. WHEATSTONE, EsQ., F.R.S.,

PROFESSOR OF EXPERIMENTAL PHILOSOPHY AT KING 'S COLLEGE, LONDON,

F. A. ABEL, EsQ., F.R.S.,

CHEMIST TO THE WAR DEPARTMENT.

INTRODUCTION,

The experiments relating to the application of electricity to the explosion of mines, of which the results form the subject of the present report, were entered upon by the late Ordnance Select Committee by direction of the Secretary of State for "'ar, the inquiry having been proposed by Professor ,vheatstone, and strongly recommended by General Sir John Burgoyne.

A Sub-committee was appointed by the Select Committee in March, 1856, to determine upon the experiments to be performed, which consisted of­

Colonel Tulloh, R.A. Lieutenant Colonel Eardley-Wilmot, R.A. Captain Younghusband, It.A. Captain Bainbrigge, R.E. Captain Boxer, R.A. Professor Wheatstone. Professor Sylvester. Mr. Abel. Mr. Anderson. Captain Scott, R.E. (Chatham), afterwards added to the list of members.

This Sub-committee met on se\•eral occasions, and witnessed experiments made with an electro.magnetic induction coil constructed by Ruhrukorff of Paris; with a hydro•electric machine, constructed by Sir \Villiam Armstrong; and with a magnet of very considerable size, constructed by Mr. Henley, which was exhibited by him at the Paris Exhibition of l '355, and was afterwards pur­chased for the use of the Royal Gun Factories. (The com,truction of this instrument was precisely the same as that of the magnets devised by Mr.

M

90 ON THE EXPLOSION OP GUNPOWDER BY ELECTRICITY.

,Vheatstone many years since for ringing electro-magnetic bells. 'l'he armature, instead of being rntating, is suddenly detached from the magnet by means of a

lever.) 'l'he contrivance of the fuzes1 and the preparation for, and general superin•

tendence of the trials at Wool wich, Chatham, and elsewhere, were undertaken by Mr. Abel. The experimental apparatus was constructed under the direction of Professor ,vhentstone, 1mrtly at the expense of the Committee, while a portion was lent by him for the investigations.

'J'he Sub-committee made three preliminary reports1 on the 24th July and 11th September, 1807 1 and 13th May, 1858, to the Ordnance Select Committee, on some of the results arrived at, and communications were also addressed to the Committee by Mr. Abel on the subject of particular fuze-arrangements and compositions prepared by him, "·ith which be bad obtained succl.!ssful results in the course of the experimental investigations carried on by him for the Sub­committee.

In consequence of the success which ultimately attended the experiments on the application of the magnet to the explosion of charges, after the production of a particular fuze by Mr. Abel, directions were given by the Secretary of State for ,var for the further prosecution of experiments by that gentleman in connexion with the Ordnance Select Committee, with a view to test, by direct application in the field at Chatham, the results which had been obtained.

Soon after the commencement of these experiments, the late Ordnance Select Committee having been dissoh·ed, and the labours of the members of the Sub• committee having therefore officially terminated, the subject was left for further elaboration in the hands of :Messrs. \Vheatstone and Abel.

\Vhen the results arrived at by the Chatham t>xperiments were conside1·ed to have been sufficiently conclusive, those gentlemen were requested by the Secretary of State for ,var to pre1mre a report on the whole of the experiments which had been instituted.

The most important subjects inquired into, and on which conclusions were arrived at by experimental investigation, as detailed in the present report, were the applications of the following sources of electricity to the explosion of charges of gunpowder:-

lst. Electro-mnguetic induction, discovered by Faraday, and employed in its most available form, as produced from the apparatus known as Ruhmkorff's Induction Machine.

2nd. Discharges from a jar or battery, charged by Sir ,vmiam Armstrong's hydro-electric machine, a new and powerful source of electricity of high tension.

3rd. Magneto-electrio induction, the electricity being developed from per­manent magnets, as also discovered by Faraday.

No experiments were made by the Sub-committee on exploding gunpowder by the dire~t charge of a voltaic battery, when the current is employed, either to produce_ rnflammation by means of the ignition of a very fine wire, as in the method h1tht!rto adopted, or to produce a spark in an explosiye mixture, rendered a good conductor, as in Mr. Statham's plan. The numerous accounts of such experiments made by Engineer officers and others, already published have rendered any repetition of them unnecessary•. '

• Seep. 1131 Vol. IV., and p. 139, Yol. YIL, of this Series,-Eo.

VI

PAllT I.

APPLICATION OF ELECTRO-MAGNETIC INDUCTION-CURRENTS TO THE

E:nLOSION OF CHARGES IN THE FIELD.

This form of electricity was first applied with practical success in 1853 by Colonel Verdu, a Spanish officer. His earliest investigations were made with the assistance of M. Ruhmkorff, at Paris. In the account of experiments sub­sequently made by himself in Spain, it is stated that, with the aid of Statham's fuzes charged with fulminate of mercury, and employing only a single element of a Bunsen's battery, he effected the simultaneous explosion of six mines in the circuit, at a distance of 300 metres from the apparatus. ,vhen he wished to produce a greater number of explosions he distributed the mines in groups of five, and interposed each of these groups in a special circuit; then, by bringing each wire, in rapid succession, to one of the poles of the machine, all the mines were exploded with such rapidity that their discharge appeared simultaneous. In one of these experiments the distance was 3,500 metres.

It is well known that the discharge of a Leyd~n battery will pass through several hundred solutions of continuity, producing a spark at each interruption. It might be expected that the induction-discharge, considering its energetic physiological effects, and its great tension, which enables it to pass through shellac, gutta-percha, and even glass, would do the same; but this is not the case; the discharge becomes so enfeebled by successive solutions of continuity that it has been found impracticable to explode with certainty more than four mines, in a single circuit, on this system.

To obviate this inconvenience, l\l. Savare, a French Engineer office1\ has de,•ised another system, which offers great practical advantages. He interposes the fuzes in derivations or branches of the principal circuit. It is easily under­stood that the mine which is nearest the apparatus, or, the fuze of which presents the least resistance to the transmission of the current, explodes in preference to the others. In consequence of the abrupt separation of the two ends of the wire between which the spark is transmitted, the curl'ent can no longer pass through this branch, the electric action is consequently augmented in the other branches, and, in a similar manner the explosions necessarily take place in them.

The most extensive application yet made of the electro-magnetic induction­machine in producing explosions at a distance, appears to be in the great opera­tions undertaken by Messrs. Dussaud and Rabattu at the port of Cherbourg in 1854, according to a system organized by Vicomte Du Moncel. At the first trial, six monster mines, containing many thousand kilogrammes of powder, were inflamed at the same moment, with a single detonation, and more than 60,000 cubic metres of rock were detached at a single explosion.

The objects of the inquiry which led to the conclusions given below were:-1. To obtain definite information with regard to the maximum number of

charges which could be fired with certainty by means of a voltaic battery of low power, and a powerful induction coil-machine.

92 ON THE EXPLOSION OF GUNPOWDER BY ELEC'l'RICI1'Y.

2. To cliscovcr the cle~criptiou of 11riming best aclaptcd for application in the fuzcs to be used with the yolta-incluction current.

3. To ascertain the extent to which an electro-magnetic coil, made of the best nnd most portable construction, vtould be likely to resist injury by ordinarily careful use, and by transport.

The coil-machine employed in the first experiments was one of considerable size and 1·ccent construction, p1cparcd by M. Rul1mkorff, and lent for the 1mrpose by i\Ir. ,,11ieatstonc. Another apparatus of similar power, but constructed for the Ordnance Select Committee by M. Ruhmkorff, with special regard to its senice in the field, was also subsequently employed in many of the experiments. A battery of cast-iron cells and zinc plates (the dimensions of the latter being 5 inches by 3 inches) was em11loyed as the most economical for general pm·poses.

In the greater number of the experiments, the current was made to pass to the charges or fuzes through one mile of copper wire, 16 gauge, insulated with gutta percha, the metallic circuit being in many :instances interrupted by an earth-connexion of about 200 yards in length.

The results furnished by a large number of experiments led to the following conclusions:-

1. Fine-grain or mealed gunpowder was fow1d to be ignited readily, by means of the induction coil, with the employment of one cell of the battery. Numerous substances of a more highly explosive characte1· were tried alone, and in admixture with gU.llpowder, in order to arrh-e at the description of priming material most suitable to aid in effecting the ignition of the maximum number of charges by means of the coil-machine. The best results were obtained with fulminate of mercury1 and with the composition which furnished such successful results with the magnet (see Part III). The efficacy and delicacy of the fuze were also found to depend in very great measure 1111011 a proper adjustment of the ,~ire-terminals which it enclosed.

2. The number of charges placed in succession in single circuit which can be fired at once by means of powerful coil•machiues, such as those used, and with the employment of twelve cells of the battery specified above, does not exceed eight (and was generally below that number) even when priming compositions of a sensitive cha.racter1 containing fulminate of mcrcm·y, gw1-cotton, sulphide of antimony, and chlorate of potash, &c., -were employed. The discharge of this number cannot, however, be relied upon with any certainty, and the employ­ment of twehe cells does not appear to offer nny decided advantage over the use ~f only fom·. The ignition of two charges can be effected almost with certainty by the employment of on1_r one cell, and the result appears to be rendered certain by the use of fom· cells.

3. By employing a rheotome for changing the dirnction of the cmTent, so as to ~ring wiresi connected with one or more charges, surcessively into the circuit, as m the system employrd Uy l\11\I. du l\Ioncel and Verdu, a considerable number can be fired in ,ery rapid succession. The result is, howe,,er, perfectly cm·tain only when a single charge is brought into the circuit at one time.

4. If, instead o~ arranging the charges ii~ a simple circuit, in the ordinary manner, each one 1s separately connected with the main wirQ and the earth (or

ON THE EXPLOSION OF GUNPOWDER DY ELEC'l'RIClTY, 93

wiih the two wires), as first proposed by 1\1. San1re, the current, when ?st~blis~ed, will distribute itself along each divided portion of the circuit, and 1gmte sunultaneous]y or in rn,pid succession the severnl fuzes which have been introduced. FiYe or six charges may thu::J be at once exploded, and a far more considerable number ignited, with a rapidity almost instantaneous, as the first of the ·very rapid succession of currents established by the coil~machiue passes through and ignites those fuzes ·which offer the least resistance1 while the others are fired iu their tw·n by the succeeding currents.

This method of exploding a number of charges at once or in very rapid suc­Ct'S!',ion is far more effici~nt than that described at pru.-agraph 3 (1up1·a), and rl'ndcrs the operator independent of the uncertainty of ffriug three or four charges simultaneously when arranged in a simple circuit; for, when the charges arc arranged in a single line, if the ignition of the whole number is not perfectly instantaneous, the explosion of the fu·st prevents the discharge of the 1·emainder, while, in the arrangement just reftn·ed to, the connection of each fuze with the instnm1ent is independent.

5. In the course of the experiments carried on with the two coil-machines constructecl by l\L Ruhmkorff (one of which was, as already stated, specially 11repared for these experiments), a considerable irregularity was obsened in the power of the same machine at different periods, although the battery-power employed was, to all ap11carance, the same on each occasion ; an irregularity which must be ascribed to defective insulation, arising from the deposition of moishu-e on some portion of the apparatus. It was also found that the arrange­ment attached to the coil-machines, known as the condensor, and upon ,Yhich the intensity of the current produced greatly depends, was Yery liable to become deranged in the transport of the apparatus and by other trifling causes. Such a derangement was found to be fatal to the efficiency of the apparatus.

'l'he perfect insulation of each coil of the secondary wire, and other somewhat delicate portions of the apparatus, were also found liable to injury from a variety of sow·ces, which it woulcl be very difficult to guard against in the employment of coil-machines for field purposes, and by persons not thoroughly acquainted ,Yith their somewhat complicated construction and their action.

Although, therefore, the system of exploding charges by means of the induc­tion coil-machine offers very in1portant advantages over the voltaic battery, employed alone (one of the principal being the great reduction effected by its use in the power of battery required), its adoption as a geueral substitute for the old system of operation with the voltaic battery cannot be recommended with confidence, principally because proper reliance cannot be placed upon the certainty and permanent uniformity of action of the inductjon coil-machine.

PART II.

EMPLOYMENT OF ARMSTRONG'S HYDRO-ELECTRIC l\!ACIIINE AS A SOURCE

OF ELECTRICITY FOR THE EXPLOSION OF CHARO ES OF POWDER,

The first proposal to employ electricity, generated by an ordinary machine, for the e.:s:plosion of mines, was made by Dr. Priestley, in 1767, but the first actual e~-periments were made in 1831 by l\Ir. Moses Shaw of New Yo1·k. By employing fuzes containing a mixture of gunpowder and fulminate of silver, he succeeded in exploding simultaneously seYeral mines, and detaching thereby large masses of rocks i but he states that he was mmble to operate during the greater part of the year in consequence of bad weather. l\Iore favourable results were obtained by Professors ,varrentrap of Brunswick and Gti.tzmnnn of Freiburg in 1842 and 1843. Employing fuzes which contained a mi.xtw·e of sulphide of antimony and chlorate of potassa, and special contrivances for eusluiug more perfect insulation, they succeeded in exploding from eight to ten mines simultaneously through 78.5 metres. Notwithstanding their precautions, the evil effects of humidity compelled them to discontinue the experiments. Still more successful results were obtained in 1845 by Mr. Charles ,vinter. By means of a fuze containing a preparation of phosphorus, he inflamed powder through the telegra.phic line between Vienna and Hetzendod, a distance of 4,906 metres.

In 1853 the Imperial Academy of Military Engineers at Vienna was charged with the inYestigation of this subject. Experiments on a large scale were con­tinued for three years, resu1ts of great importance being arrived at, which were examined and verified by a Commission, and ultimately the process adopted was introduced into the Austrian army, and employed also in many industrial opera­tions. A most interesting report of these experiments was published in 18.55 by Baron von Ebner, in the proceedings of the Academy of Vienna, from which publication the following brief particulars are extracted :-

" A portable electrical machine, in which the electricity was excited by the friction of two glass plates, one foot in diameter and four lines in thickness, was employed, in conjunction with a Leyden jar having an external coating of 276 square inches. These were enclosed in a case, the interior of which wns kept dry and heated by means of a small stove, which was fixed to it, and so arranged that the p1·oducts of combustion should not enter the case. The conductors were of copper wire covered with gutta percha. The chemical mixture in the fuzes consisted of equal parts of chlorate of potassa and sulphide of antimony, o, com­position of sufficient inflammability, but less dangerous in its use than fulminate of mercury, which was a.t first used. An extensive series of experiments was instituted, in which equal attention was paid to the effects obtained at great distances with considerable quantities of powder; by mines in holes perforated in rocks ; through great spaces under water; and by apparatus exploded under water. The greatest distance at which the explosion was attempted was four Ge~an miles. ?n ~everal occasions 50 mines were simultaneously dis­chugc<l. rn the same circuit; the fuzes were two klafters (toises) from each other,

ON THE EXPLOSION OF GUNPOWDER BY ELECTRICITY, 95

and the electric mnchine was 140 klafters from the nearest fuze. In like manner, 36 chargl"s were simultaneou-.ly explodl'd in one of the brancbea of the Danube; these charges were placed six: feet under the water, and had remained submerged during 20 hours previous to the operation. Other operations on a large scale, in marble quarries, in the beds of rivers, &c., in which considerable masses of matter were displaced, are gi ,·en in d ... tail ; they place tbe efficiency of the process beyond doubt. Its drawbacks are, that some scientific skill is required in the manipulations, that great care is needed in the preservation of the appa­ratus, and that the inductive action is sometimes so energetic that explosions are occasionally determined in other mines not intended to be included in the series, and not connected with the machine."

'l'hc experiments to be described in this portion of the report were undertaken at the suggestion of .Mr. \Vheatstone, for the purpose of ascertaining whether the hydro-electric machine of Sir "'Villiam Armstrong might not be advantageously substituted for the-Ordinary elC'ctric machine for charging a Leyden jar or battery in the field.

A small portable hydro-electric machine was constructed specially for the inquiry, and placed at the disposal of the Ordnance Select Committee by Sir ,villiam Armstrong.

It consisted of n small vertical boiler (supported on a sheet iron stand in which a grate was fixed) of two gallons capacity, pro\'ided with a safety valve by which the pressure of steam could be regulated up to 90 lbs. on the inch. 'l'he head of the boiler was provided with a cock, so as to admit of the escape of steam, to which was fixed a horizontal iron pipe, nine inches in length, and of half an inch internal diameter, and fitted with the jet and wooden cylinder which serve for the issue of the steam and the de,·elopment of the electricity. rl'he iron pipe was surrounded by a small metal box, which, when the appamtus was in use, was partly filled with water, so as to effect a partial condensation of the vapour as it passed through the pipe. A brass fork, raised to a le,•el with the jet, and capable of adjustment at different dililtances from it, served the pur­pose of conducting the electricity from the jet of steam to the Leyden jar or jars, which were placed in a sheet iron casing immediately under the steam jet. The boiler was very well adapted to the rapid genemtion of steam of considerable pressure. About twenty minutes after a wood fil·e was kindled a pressul'e of 60-70 lbs. was obtained, the boiler being one-third full of water.

To avoid the possibility of the water in the boiler priming during an operation, in which case the charging of a jar with electricity could not be accomplished, it was indispensable:-

1. That the boiler should not contain too large a quantity of water (it was found safest to eniploy it not more than one-halt' full).

2. That the water should be free from solid matter in suspension. It was therefore necessary, not only to employ perfectly clear water, but to clean out the boiler after each experiment {if spring or river-water were employed), so as to remo,•e all solid matter deposited by the boiling water. \Vith the employ­ment of rain or distilled-water this precaution was of course rendered unnecessary.

The time required to charge with electricity a Leyden jar of about l} square feet surface, when the machine was in good working order, was found to be from five to seven seconds. The rapidity with which the jnr was chnrgcd

96 ON THE EXPLOSION OF GUNPOWDER DY ELECTRICITY.

proved, under favourable conditions, to be proportionate to the pre~surc of stenm employed, the most suitable being from 60 to 70 lbs. per square 1_uch.

'l'he first experiments on the ignition of charges were conducted with only short lengths (from 12 to 50 feet) of wire, to serve as connexions between the jar and the cb11rges. The machine was worked in a locality sheltered from wind or draught. The priming composition employed in the charges was the same as that ultimately adopted in the e.x1Jeriments with the magnet (see Part III).

Two different plans were available for firing the charges:-1. By completing the circuit before the jar was charged, and allowing the

fuzes to be fired by the spontaneous discharge of the jar. 2. By allowing a definite time (about 6 or 7 seconds) for the charging of the

jar before completing the circuit. The first method would be prefe1·able for the ignition of a very large number

of charges in the same circuit, as the employment of the maximum charge attainable would thus be secured. If, however, the ignition of the charges had to be effected at a given time, it would be necessary to employ the second method.

The results obtained by this apparatus were very variable. On one or two occasions (five seconds being allowed for the charging of the jar), it was found impossible to fire six charges, lJlaced in a simple circuit, simultaneously, wit.h certainty; although, when eight, and afterwards twelve, were connected in a similar manner, seven and eleven were fired, the conditions (as to pressure, &c.) being apparently the same. On another occasion, with a pressure of 70 lbs., and an allowance of seven seconds for the charging of the jar, forty fuzes were placed in circuit, and the whole number discharged. One hundred and twenty were afterwards placed in circuit, and of these one hundred were instantaneously discharged. Attempts were subsequently made, under apparently the same conditions, to obtain a repetition of these results, but without success.

Experiments, made to effect the ignition of several charges in circuit through a considerable length (one mile) of covered wire and an earth-connexion, were only very partially successful. At first the greater portion of the wire was left in a coil, for the sake of convenience, and only a short earth-connexion (about 20 feet) was employed. Very successful, though not uniform, results were obtained, forty and fifty fuzes (the entire number in circuit) having, in some instances, been ignited, while in others a few were left in different parts of the circuit. Upon uncoiling the wire to the extent of about 600 yards, and causing the circuit to be completer} by the earth, these results could not be in any way depended upon, and on no occasion were as many as forty charges fired, the number at times not exceeding five or six.

A few experiments made with small Leyden jars charged with electricity from the ordinary cylindrical machine, were confirmatory of the comparative uncere tainty in firing a large number of charges through an extended metallic circuit of considerable length. Forty charges were fired by means of a Leyden jar containing 60 square inches of surface, the elccti·icity passing through about 20 feet of wire~circuit, but on employing one mile of wire, with an earth-connexion, the ignition of twenty-five charges, though once or twice successful, could not be depended upon.

Attempts were made on two occasions to employ the hydro-electric machine in the field. The spot selected for the experiment was the open and slopiog

ON THE EXPLOSION OF GUNPOWDER BY ET,ECTRICITY. 97

gro~d near Brampton Barracks, Chatham, known as St. ~fory's (llnd as the locality of the field works near the Royal Engineer Depot).

The machine was placed in the open air, on rising ground, and 880 yards of covered wire were employed, of which about 60 yards were extended, an earth~ connexion of that length being used in place of a second wire. Two Leyden jars, each containing about 1! square feet of surface, formed the battery. They were enclosed in a stout wooden box:, and c,·ery precaution was taken to have· them dry at the commencement of the experiments. The time to be allowed for the charging of these jars, as determined by previous experiments, made in a sheltered locality, was about ten seconds, with the employment of steam nt 70 lbs. pressure. The atmosphere was dry, ancl a slight breeze blowing, on the day of experiment. The machine was so placed that the steam-jet should be as little ns possible affected by the wind.

Repeated unsuccessful attempts were made to fire fifty charges in circuit; these were then gradually reduced to twenty, when only five were ignited, in different parts of the circuit. It was soon found impossible to charge the jars to more than a. very slight extent. This unfavourable result was ascribed partly to an interference of the slight wind with the steadiness of the jet of steam, and partly to the difficulty of maintaining the Leyden jars in a suitably dry condi­tion. The machine was removed to a trench of some deplh, for the purpose of sheltering the steam jet from the wind, but with no better result.

On a second occasion the machine was sheltered from the wind1 which blew freshly, by being placed behind a shed. Forty fuzes were placed in circuit, with 200 yards of covered wire, coiled up1 and an earth-connexion of about 20 feet. The two Leyden jars were employed, nod the whole of the charges were simultaneously ignited.

The wire was afterwards uncoiled, and the same number of fuzes were again placed in circuit, but these did not fire. On reducing the number to twenty­five, nineteen were expl()ded, six being left in different parts of the circuit.

The experiments with this hydro-electric machine were not continued, as it was considered sufficiently proved by those already instituted that the details, or rather the auxilillries, of this apparatus, must undergo some considerable modi­fications before anything like definite results could be obtained with it. Ar­rangements for securing the preservation of the jat·s in a sufficiently dry condition, and for screening the jet of steam from the prej1.1dicial influences of the wind or draught, might readily be carried into effect, and would unques­tionably contribute greatly towards rendering the apparatus more certain in its action.

"'"ith reference to the possibility of using the hydro-electric machine with advantage in mining operations, even the results already obtained are of a nature to warrant the adoption of the following conclusions:-

1. That in mining operations of very extensh·e character (the destruction of docks, bridges, &c.), where it is desirable to ignite a very large number of charges simultaneously, and at which, as is most generally the case, full appliances and conveniences are at command for thoroughly fulfilling every condition of success, there is no doubt that the hydro.electric machine is readily IJU&ceptible of very effective application, and possesses great advantages over other arrangements by which static or dynamic electricity may be applied to the same pur11osc.

N

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98 ON THE EXPLOSION OF GUNPOWDER BY ELECTRICITY.

2. That for general use in the field, the hydro-electric machine, even if _its appliances ari:, arranged in a much more effici~nt manner than ":as the case with the apparatus above referred to, is not very hkely to prove an mstrument upon the certainty of whose action, at any moment, the proper reliance can be 11laced, and principally on account of the difficulty of ensuring, in the field, the fulfil­ment of those conditions which appear esseutial to the proper generation of electricity by means of the steam-jet.

PART III.

APPLICATION OF PERMANENT MAGNETS TO THE EXPLOSION OF MINES AND

SUBMARINE CHARGES.

The ignition of gunpowder by the direct magneto-electric current, though well known to be practicable, has ne,,er yet been applied to military or industrial operations, and, so far as the reporters are aware, no satisfactory experiments showing its practical applicability to these purposes have yet been published.

The experiments forming the subject of this portion of the report were com­menced with the employment, in the first instance, of the very powerful magneto­electric machine constructed by Mr. Henley, spoken of in the introduction.

A few trials snfficed to show that, even with this instrument, gunpowder itself could not be ignited with any degree of certainty. Results obtained with Statham's and other fuzes, though superior to those fw·n.ished by gunpowder alone, were still far from satisfactory.

The first experiments were, therefore, directed to the discovery of a suitable agent to sen·e as a perfectly certain medium (or priming material) for effecting the ignition of charges by means of the magneto-electric machine.

For this purpose a variety of compositions of a more or less sensitive character were prepared for trial with the magnet. The principal of them consisted of the following ingredients:-

~ieal powder and powdered coke. Ditto and sulphur. Ditto sulphur and iron filings. Ditto ditto and carbon. Ditto and fulminate of mercury.

:Meal powder, fulminate of mercury, and iron filings. Ditto ditto and coke.

Fulminate of mercury (alone). Percussion cap composition, alone and with coke. Detonating composition (sulphide of a,ntimony and chlorate of potassa).

Ditto and iron filings. Ditto and coke.

Gun cotton alone, and mixed with some of the aboYe. Amorphous phosphurus, in admixture with oxidising agents.

It will be observed that the composition of the aboye mi.~tures was varied so as to test the sensitiveness of readily ignitable substances, both alone and when mixed with bodies which would serve as electrical conductors.

ON THE EXPLOSION OF GUNPOWDER BY ELECTRICITY, 99

Many of these compositions furnished results to a certain extent fa,·ourable; a number of fuzcs, primed with them, having been fired in succession with the magnet, and from two to four charges in one circuit having been ignited in a very few instances. But no perfect certainty of discharge was attained with any one of the above materials, the attempt to fire a fuze being frequently unsuccessful, while no difference between it and a successful fuze, containing the same composition, could be detected by careful examination.

These preliminary trials, however, established the fact that the sensitiveness (ready explosiveness) of a priming material was not alone sufficient to determine its success, but that those which possessed a certain, though not too considerable, degree of conducting power, were more readily and certainly ignited than others of a far more sensith·e character.

Some successful results obtained accidentally with one of the experimental compositions, which had become damp by ex11osure to all', led to a trial of the effect of moisture in promoting the ignition of but slightly sensitive composi­tions, and it was ultimately found that the impregnation of ordinary gunpowder ,vith a small amount of moisture (by an expedient similar in principle to one adopted with considerable success by Captain H. Scott, R.E., in connexion with charges to be fired by the induction coil-machine), rendered its ignition by means of the magnet a matter of certainty.

Some important precautions were, however, indispensable to the attainment of this definite result. If the slightly damp powder were employed in a finely­divided condition, it very frequently became caked between the wire-terminals in the fuze, ancl the cw-rent would then pass through the composition without igniting it. This was found to take place occasionally, even when the powder was employed in its original granular condition. Several attempts were made to overcome this difficulty by modifying the form and position of the terminals, and an arrangement of a completely successful nature was eventually coutriYed, in which only the sectional surfaces of the extremities of the terminals, which consi:sted of flue copper wire (23 gauge, or i 0th inch diameter) were ex11osed in the interior of the fuze so as not to project at all. The prepared gunpowder, therefore, simply rested upon the surfaces, and a perfect uniformit~· in the action of the fuze was attained. The priming composition consisted of fine-grain gun­powder, which had been soaked in an alcoholic solution of chloride of calcium, of a strength sufficient to impregnate the grains with from one to two IJer cent. of that salt. The prepared 11owder was exposed to the air for a short time, to permit of a sufficient absorption of moisture by the deliquescent salt.

Upwards of 500 quill-fuzes (of the description employed for firing gmIB), primed with the prepared gunpowder, and fitted with the arrangement of the terminals above referred to, were fired with the large le,er-magnet. 'l'he failures did not amount to more than 3 per cent., and were all proYed to be due to defective manufacture.

In the experiments with these fuzes, one or two simple arrangements (already referred to in Part II.) were successfully employed for effecting the rapidly suc• cessi ve discharge of a series of fuzes.

This fuze (which was submitted to the Ordnance Select Committee by l\Ir. Abel, in a letter dated 29th October, 1857,) was found to be easy of manufacture q.nd permanently effective. ,vhile, however, it presented a certain means of

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100 ON TIIE EXPLOSION OF GUNPOWDER DY ELECTRICITY,

effcctinO' the i,,.nition, by the aid of a pow·erful magnet, of single charges, or of n. large 0numbe~ to be fi~•cd in moderately rapid successi?n, ~t ':as inapplicable to the ignition, with certainty, of more than one charge m circuit.

A new description of pl'iming material for the f-uze was, however, prepared 800n afterwards (beinrr brought to the notice of the Ordnance Select Committee by Mr. Abel, in a leti°er dated the llth_~_Iay, 1858), whic~ greatly exceeded in sensith-eness any of the other compos1tions hitherto tried. A ·very ?m~~al sep::ll'ation of the armature from the large magnet sufficed to effect the ~gmhon of the fazes p1·lllled with this material, and the induced cunent obtamed by means of a ,ery small magnet, with a rotatory armature, such as that employed in Wheatstone'~ magneto-electric telegraph, was sufficiently powerful to produce the same result.

This priming composition consisted of a ,ery intimate mixture of sub-phos­phide of copper, chlorate of potassa, and levigated coke, the latter substance being employed to add to the conduct.ing power of the mhture, which was found otherwise insufficient. (Details of the proportions of the ingredients, their pre­paration, &c., will be found in the Appendix).

In the experiments subsequently carried on with fuzes which contained this composition, it was found that a slight residue, consisting }Jrincipally of the coke employed, occasionally remained on the surfaces of the terminals in the fuze, after its discharge, and, by forming a good conducting link between them, interfered with any fw·ther effects of the magnetic cw-rent in other directions, by the establishment of a complete circuit.

The obstacle to the complete success of the composition was entirely removed by the substitution of another material, more easily acted on by the chlorate of potassa, than the coke, and answering equally well with the latter ns a con­ducting medium, viz., the sub-sulphide of copper. .

No instance has occurred in the discharge of several thousand fuzes, primed -with the mixture of sub-phosphide and sub-sulphide of copper with chlorate of potassa, in which the terminals have not been found quite free from adherent residue, after the ignition.

The sub-phosphide of copper, which is produced at an elevated temperature, is a com1JOund of very stable character, and the mb.:ture of the three constituents is quite as unalterable as the explosive mixtures which are in general use for the pre1Jaration of percussion caps, &c. The stability of the mb:.ture has already been submitted to very satisfactory tests. Fuzes primed with it have been found to have lost none of their delicacy and certainty when tried more than two years after preparation.

Befo:e. pas:in~ to a :tn~ment of the results obtained by the aid of this priming com~os1ti~n, m m:·cstigatmg t~e extent to which magneto-electricity could be apphed with certamty to the simultaneous ignition of a number of fuzes, some little account mu~t be giYen of the properties of the priming material itself, and of the results which led to the adoption of the particular proportions giYen (see Appendix} for the preparation of the mixture.

The su~-phosp.hide ?f copper, inti1~~tely blended with chlorate of potassa, forms a m1:~ture m a high degree sens1tn~e to the effect of heat, and possessed at the same time of some pow_er of c~nductmg electricity. ,vith the employment, however, of magneto-electric machines of comparatively low power, and in cases

ON TIIE EXPLOSION OF GUNPOWDER BY :ELECTRICITY. 101

where the resistance to be overcome by the current is considerable, this con­ducting property is not sufficient to eusw·e the ignition of the mixture by n~sisting the passage of the cw-rent across the intenuption in the metallic circuit (i. e. across the small distance between the terminals of the wires in the fuze). It must be borne in mind that the striking distance, or the space between the terminals, across which the current from even a powerful magneto-electric machine will leap, is very small. ,vith the large lever-magnet, the spark could only be produced when the wires were almost in contact. Since, however, it is indispensable to the proper insulation of the wires in the fuze-arraugement, that the terminals should be at least one-sixteenth of an inch apart, it will be readily understood how essential to success, in operations with these machines, it is that the priming material should possess considerable conducting power. Hence the necessity of increasing the conducting power of the mixture of sub-phosphide of copper and chlorate of potassa; a result which, it has been already stated, was attained in the first instance by the employment of finely levigated coke, and afterwards by the substitution of sub-sulphide of copper for that substance.

:Many experiments were of course required to determine the proportions in which it was advisable to employ the conducting constituent, so as to facilitate the passage of the current through the mass as far as possible, without inter­fering too much with the sensitiveness of·the explosive mixture, or producing an almost perfectly continuous connexion between the two poles in the fuze, and thus promoting the passage of the current so greatly as to prevent the ignition of the composition,

Considerable difficulties were enco1mtered in the endeavours properly to balance these conditions, when attempts were made, which will presently be mentioned, to apply the mixture in question to the ignition of several charges in circuit. 'l'he increase in the resistance of the current, consequent on the introduction of more than one interruption in the metallic circuit, necessitated an increase in the conducting power of the mixture, which it was difficult to attain, unless at a considerable sacrifice of the sensitiveness of the composition.

It was consequently found that when the proper conditions had been attained for ensuring the passage of the current through several (five or six) fuzes in circuit, the absolute certainty of the fuze, when applied in this manner, had been sacrificed. Thus, out of several fuzes tried together, which bad been most care­fully prepared, so as to be, as far as possible, perfectly alike, the current would ignite a few, passing through the others without affecting them, and would thus point to minute differences in the conducting powers and sensitiveness of dif­ferent portions of one and the same quantity of the mixture, which, it is almost needless to observe, was prepared in such a way as to ensure the greatest possible uniformity.

The results of many experiments established the fact beyond any doubt, that the proportions of ingredients already referred to furnished a mixture possessed of the highest conducting power attainable without detriment to the sensitfre-. ness (ready explosiveness) of the material. The perfect certainty of its action, when applied in the fuze, to the explosion of a single charge by means of mag­neto-electric machines, has been proved by the ignition of at least 5,000 fazes, without failure. A large number of these haYe been fired by means of the smaller machine already referred to.

102 ON TlIE EXPLOSION OP GUNPOWDER BY ELECTRICITY.

Numerous experiments, made with the aid of this composition, established the fact that the current obtained by means even of a very powerful magneto• electric machine, when applied to the ignition of several charges arranged in succession in one cll'cuit, is Yery limited in its powers. In illustration of this it may be stated that, on trial being made of twenty-one consecutive sets of four charges, eighteen of the sets were perfectly discharged, but, in the other three sets, only two or three of the chm·ges were ignited. Out of five sets, of five charges each, only two sets were completely discharged, and in several attempts made to ignite six fuzes in one circuit only four were fired in each case. In all these experiments, when charges had escaped ignition, the current had passed through the sensitive composition without firing it. ,vhen the discharged fuzes were removed, &.nd the remaining ones properly connected, they wel'c all fired.

It bas been already stated that no beneficial effects were attained by modi• fying the proportions or ingredients in the priming composition, so as to diminish or increase its conducting power.

Three charges were therefore the most that could be ignited witli certainty by means of a powerful electro-magnetic machine, when they were arranged in succession in simple circuit.

The plan, originally suggested by ~M. Savare, of arranging the charges in divided circuits, was next tried, and iurnished far more successful results. The simultaneous ignition of twenty-:6:ve charges was repeatedly effected by means of the large magnet, each charge being connected with a separate branch attached to the main line, which led from one pole of the machine, and their connexion with the earth established by means of uncovered copper wire, the extremity of which was wound round an iron stake driven into the ground.

A still larger number of charges (forty) was similarly exploded on several occasions.

These results were all obtained with the large magnet, the current being established by rapidly separating the armature from the poles by means of a lever. By a simple arrangement for shifting the connexion of the main wire with the exploded charges, from them to a second series, similarly al'l'anged, twenty-five were also simultaneously ignited, on allowing the armatul'e to return to the poles of the magnet. It was found, moreover, that the same number could be fired by means of this magnet, even if two folds of thick brown paper were interposed between the poles and the armature, so that on depression of the lever the armature had no longer to be forcibly detached, but simply to be removed from the magnet.

These successful results (which were described to the Ordnance Select Com• mittee by Mr. Abel in a letter bearing date 23rd June, 1858,) led to trials of magneto-electric machines of comparatively small size, with revolving armatures. In the employment of these machines, it was of course not expected that any single induced current obtained from them should distribute itself among a

•number of fuzes placed in divided circuit, as was the case with the comparatively much more powerful current obtained with the large magnet, but it was hoped that the Yery rnpid succession of currents furnished by them would produce a very similar result, by distributing themselves over the different branches of the circuit with which the fuzes were connected, and that the ignition of the whole of the fuzes, though it could not be so positively instantaneous as when the one

ON THE EXPLOSION OF GUNPOWDER BY ELECTRICITY. 103

current was discharging the entire number, might yet be effected with such rapidity as practically to amount to a simultaneous discharge.

The results obtained fuHy confirmed these expectations. ,vith a small horse• shoe magnet seven inches in length, one inch in breadth, and one and three­quarter inches in thickness, provided with a revolving armature and multiplying wheels, by which great rapidity of motion could be attained, twenty•f:i.\'e charges were fired; the effect of the discharge on the ear was, however, not like that of one single explosion, as was the case in the former experiments, but like that of an exceedingly rapid 'folley, in which the explosion of any single charge could not be distinguished.

Still more favourable results were obtained with a very compact arrangement of six magnets, each about half the size of the above, de\'ised by Mr. "'heatstone, for the production of an extremely rapid succession of currents, established in such a manner that the effect would be almost equal to a continuous current (for a description of the instrument, see Appendix).

By menus of this apparatus, twenty•fi\'e charges were frequently fired in divided circuit, with such rapidity that the effect on the car was as of one explo~ sion, only of slightly longer duration than when the large maguet was employed.

On some occasions, when a slight difference was made in the velocity with which the apparatus wns worked, an interval could be distinctly noted between the first and Inst discharge, but even in those instances the effect could not be considered as otherwise than a practically simultaneous discharge.

Some sets of fifty charges in divided circuit were also ignited by means of this apparatus, but in those instances the interval between the first and the last discharge wns naturally longer, being about the same as that obsen-ed when twenty-five charges were fired by means of the small magnet above rcfcrrl'd to.

The system of firing charges by means of magneto-electricity, with the aid of the phosphide of copper fuze, having been thus far successfully developed, a series of experiments was instituted on it at Chatham, for the purpose of tho­roughly testing its certainty and applicability in the field, and subi:.equently for ascertaining the extent to which it admitted of application to the explosion of submarine charges. '!'hese experiments extended over a period of six months, and were performed under various conditions of weather.

It will readily be understood that the best and most simple methods of con­necting the fuzes, enclosed in the charges, with the branch-wires and the earth, of arranging the experimental charges for explosion, and of carrying out the various small but essential details involved in the experiments, were only gradually arrived at, and that, consequently, in many of the first experiments, which were only partially successful, the failures were traced to causes uncon­nected with the efficiency of the magneto-electric apparatus or the fuze. These imperfect results, though most indispensable to the proper elimination of the conditions essential to success, and most Taluable, therefore, at the time of experiment, would, if described in this report, necessitate the introduction of lengthy details with regard to the modes of operation and causes of individual failure, which lose their interest or importance by the side of the methods of proceeding ultimately proved to be the best, and those results which were finally accepted as conclusive. . . .

It is, therefol'e, considered advisable to confine the descnphon of the various steps in the experimental operations at Chatham to those which were ultimately

10-1 ON THE EXPLOSION OF GUNPOWDER BY ELECTRICITY,

adopted, and only to employ the results of those which may be termed the pre­liminary experime11ts, for the pm11osc of demonstrating the ncc_cssity_of ~ertnin precautions, or in illustration of points of importance for consideration lll con­nexion with the system of exploding mines.

The locality selected for the operations was the same as that spoken of in Part II. of this report. The magnetic apparatus employed in nll the field experiments was Mr. \Vbeatstone's arran gement of six small magnets just now spoken of (see Appendix for descrip tion of the instrument) , which had been fitted fot· the purpose with a compact system of multiplying wheels, nnd so arranged that the whole apparatus was enclosed in a box, the only ex posed portions being the binding screws for the attachment of the wires, a handle for setting the armatures in motion, and a key, by the depression of which, at a given signal, the circuit could be completed.•

'l'o employ the instrument at any moment, the following were the operations necesrnry :-

The insulated wire and the copper wire passing to the earth were fixed to the apparatus by means of the binding screws; the instrument was raised from the ground by being placed on its packing-case; at that height a man could operate with it when in the kneeling posture.

At a signal II ready," the handle was turned with one hand, so as to cause the armatures to revolve with the greatest possible Yelocity, whilst the other htJ.nd was pressed against one corner of the instrument, close to the key, so as to steady the box and to be ready at the signal "fire/' to depress the key with the thumb.

The connexion of the instrument with the earth was effected as follows:-A moderately clean spade was selected from among those used by the men in

digging holes for the charges. One end of a piece of stout copper wire was placed under the edge of the spade, in such a manner that when the latter was firmly forced into the ground it was pressed by the earth on both sides against the iron surface. The 1)rotruding wire was wound once 01· twice round the bottom of the spade-handle, and then attached to the binding screw of the magnet.

The gutta-percha-covered wire used in the experiments haYing been in occa­sional service at Chatham for some years, the coating had sustained some injury in two or three places. Such defects were protected from possible contact with the earth by means of waterproof cloth or sheet India-rubber. The total leugth of wire used was 881 yds., of which 600 were extended, lying along the ground.

The instrument was placed on the glacis of the raYelin in front of Cumberland Bastion, the ground sloping gradually towards the spot where the charges were e,q,loded.

To the extremity of the covered wire a number (from 12 to 25) of pieces of similar insulated wire, Yarying in length between three and six yards, and serving to connect it with the individual charges, were attached in the following manner :--About six inches of the extremity of the ma.in wire and of each of the branch-wires were laid bare, and cleansed; the end of the former was then surrounded with those of the latter (placed in an opposite direction}, and the ~hole tightly twisted together by means of pliers, so as to be brought thoroughly lllto contact with each other and with the main wire. The twisted wires were

• The instrument employed in these experiments was subsequently purchaaed for the Royal Engineer Eitablisbmeut at Chatham.

ON THE EXPLOSIO:Y OF GUNPOWDER BY ELECTRICITY. 10a

then bound round with moderately fine copper wire, which was made to bring every portion of the exterior of the bundle into connexion. The joint was made rigid with pieces of stick tied against it, and the whole securely enveloped in a piece of waterproof cloth or canvas, to protect it from damp and contact with the earth.

These connexions, though of a very rough description, and most readily prepared by any soldier, were thoroughly effectual. No instance occurred, in the whole of the experiments, of the failure of a charge, which could be attributed to an imperfect connexion of its branch-wire with the main wire.

The following was the method adopted for connecting the fuzes with their 1·es1Jective branch-wires and with the earth:-

The fuzes, as they were manufactured, were always fitted (as shown in Fig.10) with two pieces of covered wire twisted together. They were thus ready fol" insertion into the bag or other receptacle containing the charge of gunpowder, the ends of the covered wires protruding from the opening of the latter to a convenient distance for effecting the junction with the branch and earth-wires. The extremities of one of the other fuze-wires and of a branch-wire {from both of which the gutta-percha was removed to a distance of about two inches) were counccted by hooking them firmly one in the other with pliers (in the manner shown in Fig. 11). A piece of fine copper binding wire, about six or eight inches in length, was then twisted over the whole of the connexion, and the joint was finally enclosed in a small wrapping of oiled canvas, in a manner similar to that adopted at the principal junction with the main wire.

The extremity of the other fuze-wire was attached to an uncovered copper wire of sufficient length to bring the whole of the charges into connexion with each other in this manner. The wire was fixed in a convenient position by being twisted round short stakes or pickets driYen into the ground, and its extremities were buried in the earth, being attached either to spades, as already described, or to zinc plates about eight inches square.

The very rapid and comparatively rough manner in which these various connexions were made (the tedious operation of brightening every metallic connexion, so essential with the employment of the voltaic battery, being dispensed with), and their universally efficient character, were particularly commended by the officers and men who witnessed and assisted in the experi­ments.

,vith reference to the earth-connexion, the employment of large metallic surfaces was also proved, by repeated experiments at Chatham and ,voolwich, to be superfluous. The simple insertion, into the ground, of the uncovered extremities of the fuze-wires was found to afford a perfectly sufficient connexion for ensuring the ignition of the charges. The plan above described of connecting together the whole of the charges was, however, adopted as being undoubtedly the most certain mode of proceeding.

The largest number of charges which it was attempted to fire at once at Chatham was twenty-fo•e. 'l'he ignition of twelve charges was repeatedly effected, and with such rapidity as to have the practical effect of a simultaneous discharge of the whole. VVith twenty-five charges, the interval between the first and last discharge waa very decided1 being certainly longer than when the same

0

106 ON TIIE EXPLOSION OF GUNPOWDER llY ELECTRICITY.

number of chnrges were fu·ed at Woolwich with the employment of a grenter length of wire, of which, however, the larger portion was coiled up, the space between the earth-connexions being only about one-half of that introduced at Chatham; yet it was considered that even the ignition of the twenty-five charges (at a distance of 600 yards from the magnet, and with the em11loyment of 881 yards of covered wire, and, in addition, about 100 yards in the form of branch-wires), was effected with sufficient rapidity to allow of that number being employed in cases where a simultaneous discharge was required.

Another instance of the apparent effect of increased resistance (in the form of an increase in the length of wire laid out) in diminishing the rapidity of dis­charge, was observed in the employment of one branch-wire of four or five times the length of the others. A distinct interval was noted between the explosion of the other (eleven) charges and that of the one attnched to the longer branch• wire.

Experiments were made to ascertain whether the employment of a second insulated wire, in the place of 600 yards of earth-connexion, would modify the rapidity of ignition of a number of charges; but no difference of effect was observed.

It need scarcely be stated that in dealing with electricity of induction, defects in the insulation of the main and branch-wires had to be very carefully guarded against. Several failures in the first experiments were eventually traced to some defect of that kind. An instance even occurred, before the proper method of protecting the connexions of the charges with the insulated wll'es was adopted, in which the deposition of moisture upon the gutta-percha-covered wire, near the charge1 prevented the ignition of the latter, by forming a connecting link between the extremity of this wire, where it was exposed and attached to the fuze, and the uncovered wire leading to the earth in consE!quence of the two wires being in contact at a distance of several inches from the fuze.

It is therefore always a preliminary precaution of primary importance, that the insulating covering of the wire to be employed be carefully inspected while the latter is being laid out for use, and that any imperfections be protected from possible contact with the earth or from the access of moisture; a result readily attainable by the application of some waterproof envelope to the injured portion.

The experiments instituted at Chatham with the object of applying the magneto-electric current to the ignition of sub-marine charges were attended with greater difficulties than those which served to test the system in its appli­cation to land operations; nevertheless, the results ultimately attained were also of a character to lead to definite and favourable conclusions.

The method of establishing the connexions of a charge with the wire and the earth differed naturally in some respects from the mode of proceeding ah-eady described.

The charges of powder were contained in canisters of block-tin carefully soldered, so as to be water-tight. Auy vessels of this material, such as turpen­tine cans, may be employed, provided they be perfectly coated inside with marine glue, or some other description of varnish.

The fuze, with two ,vires attached ns before, the one a few inches lonO'er than the other, was inserted into the charge, and fixed in its proper positio1;in

ON TIIE EXPLOSION OF GUNPOWDER BY ELECTRICITY. 107

the canister by means of a loose-fitting bung, pushecl a little distance into the neck, nnd cut out on one side, so as to admit of the passage of the longer insulated wire, while the bare part of the shorter wll'e was firmly pressed by the cork against the inside of the neck. The latter was then completely filled up with melted gutta-percha, and the extremity of the short nncovered wU:e was bent back over its side, so as to be in close contact with the metal sw·face. In this manner the enclosed fuze was brought into good metallic connexion with the wet earth or watar by which the canister would be snrrounded. (See Fig. 12.)

The insulated wi.1·e projecting from the mouth of the canister was connected with one of the branch-wires in the manner already described; but, in order thorougbly to protect the connexion from the water in which it would become immersed, a piece of ,ulcanized India-rubber tubing of suitable length, and a tin tube rather longer and wider than the latter, were slipped on to the branch­wire, before it "'as joined to the fuze-wire, and when the junction had been effected, the India-rubber tube was pulled o·rnr it, and tied very ffrm)y at both ends on to the gutta-percha covering of the wires. (See Fig 13.)

A small quantity of cement (consisting of bees-wax and turpentine) was rubbed in between the latter and the ends of the India-rubber tube, so as thoroughly to ensure the exclusion of water, and finally, the tin tube was pulled over the joint, and fixed (by compressing the:cnds), for the purpose of imparting rigidity to the junction, and thus protecting it from injury by a sudden twist or strain. By these arrangements, when carried out with moderate care, tb,e perfect exclusion of water from the charge, and from its connexion with the branch-wire, was effected.•

The first trials of these charges were made in a shallow canal with a mud bottom, and from which at the time of experiment the water was receding so rapidly, that btfore the whole of the charges had been immersed several of them were left half imbedded in the mud. Twenty-five charges were arranged, of which 13 were exploded, though less rapidly than in the experiments on land. On the next occasion, when twenty-five charges were regularly surrounded by water (simply resting upon the firm bed of a pond of some depth), only four of the charges were exploded. Several other attempts were made to fire a smaller number of (ten and five) chnrges, similarly immersed, but in every instance only four were ignited. A careful exnmination into the cause of the invnriable explosion of so comparatively limited a number of charges under water led to the following :explanation.

• Jn an equipment prepared a few months ago for effecting sub.marine explosions, by means of the magnet, in China, stout bags of vulcanized India.rubber (as proposed by Captain the Hon. G. Wrottesley, R.E.) were provided for the reception of the charges. These bags were fitted with sockets and screw.plugs of gun metal. The fuzes furnished for use with these bags were attached to two pieces of covered wire, about 18 inches long, which were enclosed side by side in a cylindrical plug of gutta-percha about 4 inches long, and carefully made to form one mass with the coating of the enclosed wires. (See Fig. 14.) This plug was made to fit pretty tightly into a thick washer of India. rubber, contained in the socket of the bag. An inner screw-socket, which was brought to bear with great force upon a metal ring resting on this washer, when the plug had been inserted, compressed its internal surface against the latter in such a way as to . ensure a perfectly water-tight joint.

, I

!OS ON TlIE EXPLOSIOX OP GUNPOWDER DY ELECTRICITY.

It will be remembered that the explosion of numerous charges in a divided circuit by the magneto-electric apparatus wi_th revolving armatures, ~s _effec~ed by the action of an exceedingly rapid succession of currents. Tho _rnp1dit! with which they follow each other, however great, cannot equal that with which the terminals of a fuze, exploded in a small charge under water, come into contact with the latter after the explosion. 'l'hc instant this occurs a complete circuit is established thl'Ough the water, and any further action of the cw-rents is at once arrested.

By the time, therefore, that four charges had been ignited in extremely rapid succession, so as to be apparently exploded at once, a sufficient interval of time had in reality elapsed to allow the water to re-occupy the spoce filled for a brief period by the gaseous products of the first explosion, and thus to rush in upon and complete the circuit with the terminals of the fuze. It appears probable that, with the employment of larger charges of powder (about eight ounces was the quantity exploded in each charge), when the volume of water displaced by the explosion would be more considerable, a greater number of charges would be exploded before the circuit could be completed by the water. No opportunity occurred, however, during the experiments, of ascertaining this by actual trial.

The instances, howcver1 in which it is indispensably necessary that a number of charges should be exploded together, suspended in water, or simply resting on the ground below, and being in immediate contact on almost all sides with water, appear to be of exceptional occurrence.

It is believed that charges are generally so arranged for submarine operations as to be partially or completely surrounded by the objects upon which the force of the exploding charge is to be exerted, and that they are eYen at times firmly ti.xed in their position by being partly or wholly embedded in sand, mud, or some similar material. In such cases, the resistance to be overcome by the explosion is greater than if, under conditions otherwise similar, the charges were simply in direct contact with the water, and hence the intenal is increased which must elapse before the water can complete the circuit.

'l'he results of some experiments made at Chatham appear to show that, under such circumstances, the number of charges ignited at one time by the magneto­electric apparatus must be greater than if they were simply immersed in water. One experiment has already been mentioned, in which thirteen charges out of twenty-five were exploded at one time, most of them being imbedded in mud.

On another occasion the charges were placed in small pits filled with water, the canisters being co,•ered in with mud beneath the latter. Nine of the charges were fired; the branch-wire of the tenth was accidentally severed at the moment of the explo::.ion, from its lying across one of the pits,

An attempt was made to fire simultaneously fourteen charges similarly arranged, by the current obtained from the large lever magnet, but only seven were exploded ; the other seven were fired on a second trial. It should be mentioned that the length of extended wire and the interval between the earth-connexions were greater in these experiments than in those made at ,voolwich with the large magnet, in which twenty-five charges were fired with perfect certainty by the single current obtained from it. Possibly the very great difference in the results obtained might have been partly due to some

ON TUE EXPLOSION 0~' GUNPOWDER llY ELECIRICITY. 109

minute defects in the insulation of the branch~wires employed at Chatham, which escaped notice on the inspection of the wires, but sufficed to diminish the intensity of the current when these were immersed in water.

It is most difficult, eyen in a long continued series of carefully observed experiments, to separate the pure results furnished by the application of a system, such as that which forms the principal subject of this Report, from results which are brought about, or, at any rate, greatly modified by accidental circumstances. It appears, however, apart from the latter, that in the applica­tion of electricity (whether frictional or magnetic) to the explosion of charges the effects to be produced by the current are modified by the resistance offered to it in its pa.ssage along wil'es of very considerable length, and that the effects of the current seem Yery much less when the insulated wire is extended than when it is employed in the form of a coil.

The retardation in the explosion of several charges in divided circuit by a rapid succession of currents, and the diminution in the number of charges fired by one single powerful current, both of which reimlts were repeatedly noticed in the course of the many experiments with the magneto-electric and hydro­electric machines, could only be ascribed to modifications in the intensity of the electricity by the greater resistance which is encountered.

CONCLUSIONS.

The conclusions arrived at by a careful consideration of the results furnished by the series of experiments on the application of magneto-electricity to the explosion of charges are as follows:-

Firstly. The explosion of a single charge of powder by means of the phos• phide of copper fuze and a magneto-electric apparatus (even of the smallest size generally manufactured) is absolutely certain.

Secondly. The phosphide of copper fuze is as safe and permanent as any arrangement employed in the service for the ignition of gunpowder by the aid of friction or percussion.

Thirdly. \\'ith the employment of a magueto-electric apparatus similar to that used in the Chatham experiments, and termed by Mr. Wheatstone the "magnetic exploder," the ignition, at one time, of fuzes Ynrying in number from two to twenty-five, is certain, provided these fuzes are arranged in the branches of a divided circuit in the manner described. To attain this result it is only necessary to employ a single wire, insulated by a coating of gutta percha or India-rubber, and simple metallic connexions of the apparatus and the charge with the earth.•

Fourthly. The explosion of from twelve to twenty-five charges may be effected in the above manner, at a distance of at least 600 yards from the apparatus, with a rapidity which in its results will in all probability have the practical effect of a simultaucous discharge. This statement refers only to chnrges on

land.

• An uncovered wire, raised from the ground, and supported on pole& by insulatora,

might also be succes~fully applied.

110 ON THE EXPLOSION OF GUNPOWDER IJY ELECTRICITY,

Fifthly. The number of sub-marine charges which can be e11plocled with cer~ to.inty at one time by means of the magnetic exploder, is more limited; but if such charges are entirely or partially imbedded in sand, mud, or other dense materials, fi·om two to ten may be fixed with certainty. If the charges are suspended in, 01· immediately in contact with wate1·, only four can be exploded nt one time with certainty. This statement is based upon the employment of small charges (about 8oz.), and it is possible that with hea,ier charges n larger number may be exploded.

Ily the employment of separate w:ixes, leading fi·om the instrument to each charge, or by adopting Vicomte du 1\loncel's rheotomic a1Tangement (referred to in Part I.), there is little doubt, howeYer, that the results obtained with the magnetic exploder in submru-ine operations would be quite equal to those definitely established for the ignition of charges on laud.

Sixthly. The only important precautions to which it is necessary to attend rigidly, in order to ensure uniform success in the application of the magnet, are the proper insulation, throughout, of the main wire and branch-wires leading from the instrument to the charges, and the thorough protection of all con4

nexions of wires from the access of moisture. Seventhly. The system of firing charges by magneto-electricity possesses

important advantages o,er the application of the voltaic battery to the purpose. The following are the principal of these :-a. The magnetic exploder is at any time ready for immediate employment;

it is easily transported by hand, being of small dimensions and weight; it is not liable to injw·y or derangement, provided the most ordinary care be applied to its preservation and transport; it may be employed for many years without suffering any important diminution of its power; and, as all arrangements in connexion with the instrument are mechanical, any injury which they may sustain can be repah-ed by ordinary workmen.

b. The magnet-fuze is more certain than any fuze-arrangement applied with the voltaic batteries. It may be preserved for a great length of time in any climate, and will bear very rough treatment without chance of injury.

c. The implements and materials required for carrying on operations with the magnet, in addition to the inst.rument, the wire, and the fuzes, are ,ery few in nwnber, inexpensive, and readily replaceable; they occupy but little space, and require no more care in their transport than ordinary artisans' tools. (A list of the requisites is given in the Appendix, to which is added some acco1mt of the proximate expense of the principal items.)

d. All the operations necessary in the employment of the magnet (the con­nexion of the fuzes with the instrument, their introduction into the charges, and the explosion of these), are of the simplest possible character, and can there­fore be performed by any person of the most ordinary intelligence.

It can be confidently affirmed that the general certainty of the magneto­electric arrangement is decidedly greater than that of voltaic batteries, and that the necessity of ensw·ing a proper insulation of wires and connexions, though it may be regarded in the light of a difficulty by those accustomed to carry on operations with the ,oltaic current, is in reality a condition which may be fulfilled readily and with certainty by the use of wry simple means and pre­cs:c.tions.

ON THE EXPLOSION OF GUNPOWDER BY ELECTRICITY. 111

There is little question thJtt with battery-power of great magnitude, and with the successful fulfilment of the numerous indispensable conditions and precau­tions (which long experience has shown to be almost a matter of chance), it is possible to fire at one time a very much larger number of charges than those which haYe been quoted as the greatest task to be accomplished with certainty by the apparatus proposed for general use.

It hns, however, been stated by high military authorities on these subjects, that the instances in which it is required to fire more than frbm tweh-e to twenty charges at one time ru:e quite exce1)tional, and that, indeed, twclYe may be con­sidered as the greatest number of charges which it may be necessary to ap1Jly in all general operations.

In special cases, such as the destruction of ,·ery massive works, where it would be advantageous to apply the force of exploding gunpowder simultaneously to a very large number of different places, the employment of arrangements of a special character is always admissible.

The reporters are strongly of opinion that the instrument which, in such instances, will furnish results far surpassing in magnitude and in certainty those attained by the most powerful "oltaic batteries hitherto applied, is the hydro­electric a1,paratus of Armstrong, which, they feel convinced, may be so arranged in its details as to admit of ready application with confidence in the most extensive mining operations.

A considerable number of experiments would, however, still be required before its adoption in such instances could be confidently recommended.

For all operations of a general character, however, it is considered that the results obtained, up to the present time, have satisfactorily proved that the system of exploding charges, whether in the form of mines, or for proof and experimental practice with guns, by a magneto-electric current, is, in point of certainty and simplicity, superior to any other which has hitherto received application, and that no impediment whatever exists to its being at once adopted in military operations.

C. WHEATSTONE.

F. A. ABEL.

112

APPENDIX.

1.-DESCRIPTION OF "\VHEATSTONE'S MAGNETIC EXPLODER,

The magnetic apparntus employed in all the field experiments wns designed espccfolly for the purpose by Mr. \Vhcatstoue. . .

It consisted of sb;: small magnets, to the poles of wluch were fixed soft iron bars surrounded by coils of insulated wire. '!'he coils of all the magnets were united together, so as to form, with the external conducting wire and the earth, a sino-le circuit. An axis carried six soft iron armatures in succession before each 0of the coils. By this arrangement two advautages were gained; all the magnets simultaneously charged the wire, and produced the effect of a single magnet of more than six times the dimensions, and at the same time six shocks or currents were generated du.ring a single reYolution. of the axis, so that, when aided by a multiplying motion applied to the axis, a very rapid succession of powerf~l currents was produced. A single large magnet with a rotating arma­ture could not be made to produce the same succession of currents without the application of considerable mechanical power. Another peculiarity of this apparatus was that the coils were stationary, and the soft iron armatures alone were in motion ; by this deposition the circuit during the action of the machine was never broken. In the usual magneto-electric machines with rotating armatures the circuit is necessarily broken twice dw·ing every re,,olution, and this frequently gives rise to irregularities in the production of the cul'l'ents. By the construction adopted, the cunents can never fail to traverse the circuit.

The total weight of the instrument, enclosed in a case, as described in the Report, Part III., was 32 lbs. 11 oz. It was enclosed for transport in a small packing case, weighing about 7 lbs.

Some further important improvements have recently been effected by Mr. Wheatstone in the magnetic exploder, whereby its size and weight have been very considerably diminished.

Il.-DESCRIPTION OF THE CONSTRUCTION OF THE MAGNET-FUZES INVENTED

BY MR. ABEL, AND OF THE MODE OF PREPARATION OF THE PRIMING

MATERIAL USED IN THE FuzE.

The fuze for mining purposes consists of-a. A head for receh-ing the wires which connect the fuze with the m.ao-net

and the earth ; 0

b. Of the insulated wires, with the terminals of which the prlluino-material is in close contact; 0

c. Of a small_ cartridge ~r. charge of powder, enclosing the terminals, upon which the sensitive composition rests.

The fuze-head, whi~h is of box-wood, contains three perforations (Figs. 4 and 5) ; the one, passmg downwards through the centre, receives about two inches of double insulated wire, a, a, (Figs. 4 and 5, two cop11er wires of 24-gauge

ON THE EXPLOSION OF GUNPOWDER BY ELECTRICITY, 1J3

0·022-inch diameter, enclosed side by sicle, at a distance of 'l\th inch, in a coatino­of gutta-percha of ½th inch diameter)•; the other two perforations, which a1: parallel to each other on each side of the central one, and at right angles to it, serve for the reception of the circuit-wires. The arrangement for secm·ing the connexion of these with the insulated wires in the fuzes is as follows :-

The piece of double covered wire above referred to is originally of a sufficient length to allow of the gutta-percha being removed from about one and a half inches of the wires. These bare ends of the fine wires, which are made to pro­trude from the top of the fuzc-head, are then pressed into slight grooves in the wood, proYided for their protection, and the extremity of each is 1mssed into one of the horizontal perforations in the head, in which position it is afterwards fixed by the introduction into the hole of a tightly fitting piece of copper tube, so that the wire is firmly wedged between the wood and the exterior of this tube, and is thus at the same time brought into close contact with a compa­ratively large surface of metal. It will be seen that it is only necessary to fix one of the ch-cuit-wires into each of these tubes1 in the opposite sides of the f-uze­heacl, in order to ensure a sufficient and perfectly distinct connexion of each one of them with one of the insulated wires in the fuzc.

The extremity of the double covered wire, which protrudes to a distance of about three-quarters of an inch from the bottom of the fuze-head, is J)rovided with a clean sectional surface by being cut with a pair of sharp scissors, care being taken that the extremities of the fine copper wires are not pressed into contact by this operation.

A small cap of about half an inch in length is then constructed of thick tin­foil (Figs. 4 and 6), into which is dropped about one grain of the priming material. The double wire is then inserted, and pressed firmly down into the cap, so that the explosive mixture is slightly compressed, and in close contact with the surfaces of the wire-terminals.

The cap is fixecl by winding a piece of twine once or twice round its upper part, tightening the ends of this, and then removing it. The actual fuze is then ready for enclosure in n small charge of gunpowder. (Figs. 7 and 8.) The powder is contained in a paper case tied on to the head, or in a cylinder of sheet tin tightly fitting on the fuze-head at one end, the other, after the introduction of the powder, being closed with a plug of clay or plaster of Paris.

It is advisable (as stated in tbe body of the Report), to have the fuzes ready fitted with pieces of insulated wire about two feet in length, twisted together as shown in Fig. 10. The ends of the wires, after they are passed through the connecting holes in the fuze-hend, should be tightly fixed in their position by the introduction of a short piece of copper wire.

The phosphide of copper fuze for firing cannon (Fig. 9) differs slightly in its construction from the mining fuze. The fuze-head is longer than in the latter, and of such a form that the double coYered wires (which are fitted into it in the mauner already described) are completely enclosed in it, the lower extremity of

• This description of double wil'e has been prepared by the Gutta Percha Company for this particular purpose in considerable lengths (300 yards), from which the pieces of requisite length are cut off as required. The insulation of the two wires has been found perfoct throughout the whole length manufactured at one time,

p

I ' I

114 ON TIIE EXPLOSION OE' OUNPOWDER DY ELECTRICITY.

its central pcrforo.tion still remaining free to receive the top of the quill or copper-tube chargecl with powder, like the ordinary tube arrangement for firing cannon.

The priming material contained in the fuzc is prepared by reducing separately to the finest possible state of division the sub-phosphide of copper, sub-sulphiclo of copper, and chlorate of potassn, ancl then mL~g these 1mwdered substances Terv intimately, in the proportions of 10 parts of the first, 45 of the second, and 15 Parts of the third, by 1·ubbing them well together in a mortar, with the ad,li~ tion of sufficient alcohol to thoroughly moisten the mass. The mixture is afterwards carefully dried, and may be safely preserved in closed vesscLs until required.

UL-LIST OF lMPLEl\IKNTS, &c., REQUIRED FOR OPERATIONS WITH

THE MAGNETIC EXPLODER.

1. Magnetic Exploder.

The cost of a thoroughly sufficient instrument is inconsiderable, but varies natm·a.lly with its size and power.

The large lever-magnet referred to in the Report was purchased by the ,Yar Office for £70, but au efficient magnetic exploder will cost, according to the number of magnets of which it is composed, from £16 upwards.

2. Insulated Wire,

In addition to the main wire, a quantity must be pro·rided sufficient for making the \'arious branch connexions. The wire which may be employed is of two kinds:-

a. Copper wire of 16-wi.re gauge, covered with a coating of gutta•percha of ¼-inch diameter. The cost of this wire is at the rate of from £27 to £29 per mile. ( Although the use of a somew·hat thinner wire is admissible, it is consi­dered desirable for all general purposes to use a wire of the above diameter.)

b. Copper wire of same gauge as the last, coated with India-rubber, and pro­,ided "ith au efficient protective hemp covering. The diameter of this wire would be about :l--inch, ancl its cost would not exceed £25 per mile.

A wire of this description is conshlered to possess undoubtccl advantages o,·er guttn.-percha covered wire. The very uncertain durability of gutta-percha, when exposed to the action of air ancl light, renders the excellent insulation which it affords to wire, ns long as the coating continues perfect, a matter of uncertainty after the wire has been in use for a comparatively short period.

'l'he coating frequently becomes in time so rigid, and almost brittle, that it is rcaclily injured by use, and will sometimes not bear a slight bend without era.eking. Some of the wire employed in the experiments referred to iu this Re-port, and the coating of which was origina11y perfect in condition, is now quite unfit for use, the gutta-percha having become brittle, and in some places puh·erulent. Other pieces of wire, procured at about the same time, and used with the above, nre apparently still in good condition.

i\161£11.:S .!\. & :i:'tf 'E 'T i:nrr z ::& .s ,

fov

MINES AND ORDNANCE.

I

J

ON TIIE EXPLOSION OF GUNPOWDER IlY ELECTRICITY, 115

The India•rubber coating also appears to suffer some change after long expo­sure to air and light. This change is, howenir, n1)1)arently not detrimental to its plasticity. The hemp coating, with which the wire above refen-ed to is pro,1ided, to protect the India-rubber from injury in use, will also in all proba­bility prevent it from suffering change. Under any cil'Cwnstances, however, there is very little doubt that mnch greater dependence can be placed upon the permanent insulation of wire coated with India-rubber. The compnrath·ely low temperntm·e at which gutta-percha becomes very soft (the average temperatw·e of tropical climates being quite sufficient to produce that result) is a defect which gives the India•ntbber another important advantage over that substance.

Other good insulating materials have recently been prepared, with special reference to their employment in hot climates. The experience gained up to the })resent time with respect to their durability is, howeyer, too limited to allow of their being positively recommended for employment.

3. The magnet fuzes. The cost of the fuzes is calculated at threepence half-penny each.

4. Copper wire of 16-gauge, for earth and other connexions. 5. Fine copper binding wire (25-gauge). 6. Oiled can,·as, or other cheap waterproof material. 7. Vulcanized India-rubber tubing, ~-inch internal diameter. 8. Twine. 9. Pliers (for cutting and twisting wires.) 10. Knife ( commou, for cutting gutta-percha, &c.) 11. Box of cement (mixture of beeswax and turpentine, or any other good

soft cement of a similar kind.) 12. One or two small files (for cleaning wires, after removal of gutta percha.) 13. Wooden pickets. 14. Small pieces of thin wood for stiffening connexions (any wood obtained on

the spot will do.)

llG

PAPER XII.

ON THE DESTRUCTION OF BRIDGES.

BY GEN. SIR J. BURGOYNE, BART., G.C.B., &c.

The following translation of nn Austrian account of the attemptccl dcstruct~on of the bridge over the Ticino at Sau Martino, near 1'fogenta and Buffalorn, during the campaign of 1859, is of interest•.

"General instructions were issued to the Austrian Eugineers in 1858, for mining the new bridges and viaducts in readiness for blowing them up, as well ns a special order to prepare a project for destroying the old bridge at San 1\'.lartino. It was therefore proposed to bore cylindrical holes 8 inches in diameter hori­zontally across it, .over two of the arches, according to a plan recommended in the instructions.

This operation was however considered objectionable, because it might affect the stability of the arches, and the explosion would not be certain to destroy the bridge, for the chamber of the mine having but little brickwork over it, the explosion might take effect in an upward direction only. It was therefore sub• sequently proposed to sink two shafts, each 30 inches square, in the d:ixection of the longitudinal axis of the central pier of the bridge which was to be destroyed. From the bottom of each sha.ft1 galleries, 30 inches high and 2-1 inches widet, were to run in both directions, that is four galleries in all. Each gallery was to terminate in a chamber, to contain 62 lbs. of gunpowder, and the centres of these were to be 9 feet from each other, the line of least resistance being equal to half the thickness of the pier, or 6 feet 4 inches.

The Committee of Engineers, ordered to report on this plan, made a third proposal. The shafts, galle1·ies, and chambers were to be replaced by four cylindrical holes 7 inches in diameter, bored ,,ertically, at the bottom of each of which there was to be a chamber 6 inches in diameter. Seventy pounds of 40°

• The destruction of this bridge was of the greatest consequence to the Austrians, for when they retreated from it, leaving it in such a state as to be passable for troop!!, the French were enabled to cross in sufficient numbers to win the battle of Magenta before their opponents were concentrated. Between the Ticino and the town of Magenta however they encountered another obstacle, viz., tl1e Grand Canal, which would have checked them for a long time if properly defended; but although the four bridges across it were mine<l, only two of them were blown up; and near one of these the Austrians left some planks wl1ich enabled the French easily to restore the roadway. The great im~ portance of proper arrangements. for destroying bridges thoroughly and with certainty is thus forcibly illustrated by the operations of one day.-Eo.

t These dimensions appear too small for shafts and galleries, the Austrian inch being -very little longer than the English inch,-ED.

ON TllE DE~TRUCTION 01" BRIDGES. 117

powder were l'l'qnirecl for each hole, or 280 lbs. for each pier, this calculation hi:ning been bmsed on the prc&UIDJJtion that the co•efficient g should be taken at 0·2.i5, the same os for compnct rock. ·

'l'he Committee were induced to make this proposal because they considered the making of shafts, galleries, and chambers, too difficult, and likely to affect the stability of the bridge, an apprehension shared by all the architects who were consulted.

Finally these three projects were thoroughly considered, and reported on ns follows:-

1. Consiclering the strength of the bridge, and the great thickness of its arches, which were built of granite, ns well as the weakness of the filling in above them, the destruction of an arch could not be expected by boring a cylinch·icnl hole 8 inches in diameter horizontally through the keystones, nor could the use of jumpers be recommended to make these holes, for fear of weakening the arches too much.

2. The making of shafts and galleries would be n tedious and difficult opera­tion, which would endanger the solidity of the bridge, and the chambers would moreover be liable to be flooded when the water was high, and could not be charged and tamped without difficulty.

3. The cylindrical holes proposed by the Committee of Engineers deserve the preference, provided that they were made more than 7 inches in diameter.

This proviso was made because it was considered that the diameter of cylin. di·ical chambers for blasting must not be very small, as the effect of an elongated charge placed in a narrow hole is not equal to the effect of the same quantity of powder placed in a cubical chamber, and that consequently a charge concen• trated in a chamber of large diameter must ha,,e a greater effect than an equal charge lodged in a narrow hole.

In accordance "ith these recommendations a diameter of 12 inches was adopted for the holes proposed by the Committee, whilst the canisters placed in them were to be 10 inches "ide and 3 feet high, and were to contain 70 lbs. of powder. In other respects the proposals of the Committee were adopted, and four charges were ordered to be placed in each of the two piers nearest to the abutment on the east side of the riYer. (See Plate.)

In consequence of the alterations proposed on the spot, and subsequently sanctioned, the charge of powder in each hole, the diameter of which was 12 in., only reached to b, instead of being 6¼ feet high, and reaching to a, above the centres of the voussoirs, as would have been the case had the diameter of the holes been 7 inches.

Suitable implements for boring the holes were wanting, and none could be procured at the moment, owing to the breaking out of the war. The chambers were blasted therefore with gunpowder, and the holes made were much larger than necessary, and of very irregular shape. To meet this evil and produce the necessary width and smoothness, a pole hnd to be let down into each, and the intenal between it and the masonry was filled up with bricks. The expenditw·e of powder used in this blasting was very much regretted subsequently, when another supply could not be procured, and it would then have been of essential senice.

118 ON TIIE DESTRUCTION OF :BRIDGES,

The mnnncr in which the holes had been made necessarily diminished the effect of the mines. Tho powder was deposited within a mass of unequal con• sistency, consisting of granite, mortar, and bricks, and fissures moreover had been made in the masonry during the blasting, which, though scarcely perceptible, allowed the gas to escape premntw·ely, thus considerably wea.kening the general effect.

When orders nrrh·cd during the night of the 2nd June to blow up the bridge, the chambers were filled with 70 lbs.• of powder in each, and partly tamped with sand i but it has not been ascertained whethe1· the upper part was properly filled with clay and fragments of stone.

On ignition five only of the mines exploded, with a rather strong detonation, including the four in the first pier but only one in the second.

After this unexpected failure the remaining charges were at once examined, and being found intact, were successfully exploded by means of electricity, and it was expected that the arches would then fall.

The second detonation equalled the first, but the arches did not fall. The masonry below them had been destroyed, and they had sunk at the keystones I two or three feet; the road across the bridge formed a concave line, and was full of fissures, and the balustrades, formed of blocks of stone, had been precipitated into the river.

The annexed photograph shows the condition of the bridge after the second explosion, the first pier, where all four mines had exploded, being full of fissu1·es, whilst the second pier, where one mine only exploded during the first ignition, and the three others during the second, has suffered much loss.

As there was no powder in reserve two guns were ordered to batter the parts of the bridge most injured, in order to cause the arches to fall, but without success.

The extraordinary hardness of the granite arches, the masonry of which had grown, as it were, into one mass, and was moreover probably secured with iron cramps and stone dowels not visible on the outside, explains how the arches could suddenly sink two or three feet without being ruined, in spite of the destruction of the masonry below the arches and the material change in the positions of the voussoirs consequent upon it, which, when we consider the con~ dition of the first pier, could scarcely be otherwise explainedt.

There is no doubt that if a larger quantity of powder had been placed rather higher, the arches would have fallen. Probably the result would have been the same if the quantity of powder actually used had been placed in a narrower hole, as originally proposed, when it would have reached up to a, instead of being concentrated lower down in a wider hole.

This latter opinion is justified by the success of the blasting operations at Vienna, in 1858. A charge of powder 5{- feet high, with a tamping of 45 inches and a line of least 1·esistance of more than 4 feet, placed in a bored hole 9 feet deep and 2¼ inches wide, then effected the demolition of part of a strong wall 11 feet high and some centuries old. \Ve are justified therefore in believing

• 86 lbs. English.

t From the photograph it appears that a layer of masonry 2 or 8 feet thick was blown out from the pier and that the arches sank on to a new bed.-Eo.

ON TBE DESTRUCTION OF DRIDG ES. 119

that chnrgcs of powder 6 inches in diameter, nnd reaching up to a, would have ~•d the desired effect upon !he arches of this bridge, though the charges 10 mches in diameter and 3 feet high proved abortive.

~he unsatisfactory result cannot however be ascribed solely to the extra­ordmnry finnness of the masonry, which was provided for by the charn-e beinD' ~alcalated by the highest co-efficient, but rather to the existence of other injuriou~ mfluenccs. It could not be ascertained whether the powder used actually had the supposed strength of 400; the holes were bored in a manner which neces­snrily lessened the effect of the mines; and the tnmping and ignition took place in the dawn of the day, and may not have been managed efficiently.

It would have been desirable no doubt completely to destroy this bridge, but as far ns immediate consequences were concerned the condition of the imperfectly blasted nrches compelled the enemy to throw a bridge across the riYer close to it, not being able to cross by it owing to the damage it had received."

I attribute this failure to the Austrian Engineers, who are able and scientific, having aimed at too much refinement in the operation; a refinement which may be very proper where all necessary time and means are available, but is scarcely practicable in a campaign ;-thus, the account here shows, in one part, a want of the implements necessu.ry for ma.king the openings as determined upon; a deficiency at last in the requisite quantity of powder; doubts expressed as to the powder having the particular degree of strength calculated upon; and a failure iu the ignition of three charges out of eight; all of which difficulties, it is appre­hended, might have been prorided against by adopting a more simple off-hand manner of proceeding.

In destroying a bridge in a campaign, the eystem should vary with the time and means available ;-it is rare that that which is most correct, theoretically, can be ndopt('d; and, generally, every disadvantage may be counteracted by employing plenty of powder. The object being destruction, it is of far less consequence to ha-re that in the extreme than to fail in obtaining what is required.

In campaigning it is an established principle (or at least it ought to be) to do as little injury to the country and to the inhabitants as can be consistent with what is absolutely required for military progress and success.

As regards the plan for the destruction of this bridge, had the mines fully succeeded, they would ha'\"e brought down three arches, while probably one would have been quite sufficient for the object of a temporary impediment to the enemy; and by confining the attempt to one the means available would have been more ample ; but even by the very system adopted, if the charges Lad been confined to one pier, and been effective, two arches would have been destroyed, with scarcely more than half the means required for acting on the two piers, and the operations would have been far more simple for firing the four charges instead of eight; with the same quantity of powder also, the charges would have reached the point a in the section, to which so much consequence is attached.

120 ON TlIE DESTRUCTION OF BRIDGES,

But I should have been inclined to adopt a different course altogether, and to haYe run a gallery, as small as men could work in, say from 3 to 4 feet high by about 3 feet wide ( either from the outside or from the bottom of a shaft sunk from the surface of the path or roadway), over the most solid part of the pier, that is at the level of the springing of the upper surface of the arch stones, with returns to the haunches of the arches,wbere two charges might be placed at equal distances between the two faces of the bridge; then tamping the galleries as substantially ns circumstances would allow, I should feel no doubt that tho quantity of powder, which I calculate as having been more than 680 lbs. English, would have effectually destroyed the arch, by acting as globes of compression, although the lines of least resistance would have been in other directions.

It is quite clear that the strength of the bridge, by construction and being cemented by time, rendered it quite unnecessary to fear taking any such liberties ,vith it as this preparation would have entailed.

Had the time for preparation been very short, I have little doubt but that the same quantity of powder laid in a trench over about one-fourth of the width of the bridge, in the middle, and in one mass on the very crown of the arch, would have made an openiug of considerable ,vidth at least, if it did not bring it all down, particularly if circumstances would have admitted of applying a loading of heavy stones from the parapet, over the charge.

There must haYe been some want of a power of co-operation between the services of the Artillery and Engineers, when a deficiency of powder for the mines, by the use of a part of it in blasting the boles, is mentioned as a possible cause of the fnilure, considering that a quantity, probably larger, was subse­quently expended in an attempt to complete the destmctiou by the fire of Artillery.

J. F. B.

A PHOTOGRAPH.

ION AT THE CROWN OF THE. ARCH.

f'l 9ht

,!I ; •

'

'' ., ' t: '' '' •••• 1

'' '' : ;

,:,f the ll'oter

</()_-t,..,u.._,u, J'n::t >-~~----~

121

PAPER XIII.

A LU~AR TIDAL WA VE IN LAKE MICHIGAN,

DBJIOl(ST&ATBD BY

BREVET LIEUT. COL. J. D. GRAHAM,

UNITED STATES TOPOGRAPHICAL ENGINEERS.

COMMUNICATED BY COLONEL NELSON, R.E.

Chicago, 111inois, July 19th, 1860.

To the Secretary of the American Philosophical Society, Philadelphia:

Dear Sir,-I have made all the necessary astronomical observations and electric signals for determining the latitude and longitude of twelve additional positions in the ,vest; but have been so pressed with my public duties that I have not been able to take up their computation. "\Vhen I can find time to do so, I will communicate them, as heretofore, for the " Society's Proceedings." I find that, in several instances, they will give results differing much from those given in the published maps.

I have now nearly completed a paper, which I intend to offer for publication in the " Society's Transactions," on the Discovery and Demonstration of the Existence of a Semi-Diurnal Lunar Tidal '\V ave on Lake Michigan. It is based on 9,184 observations made on the tide-gauge, at Chicago, of the elevation of the surface of this lake, between the 1st of January and the 1st of July, 1859.

The observations were c1uried on uninterruptedly, both day and night (except in a few instances, when violent storms would have rendered them inaccurate), at intervals of half an hour, as a general rule, and sometimes at intervals of fifteen minutes of time apart.

From this series of observations we deduced the half-hourly (and in two places the quarter-hourly) co-ordinates of altitude of the lake surface, compared with the time (before and after) of the moon's meridian transit, as follows . Here each co-ordinate, expresseU in decimals of a foot, is derived from a mean of 3--10 observations.

Q

122

TABLE 1.

Sh · g the half-hourly (and in two places the quarter-hourly) co-ordinates of owi:ititude of the average semi-diurnal lunar tidal wave at Clncago, on Lake

:Michigan, derived from 9,184 observations made between January 1st and July 1st, 1859.

Mean solar interY:1-l of time before or after the moon's meridian transit.

H, Mo

jrrn 5.00 4 30

·g -~ g~

1 B lrn 1.30 .3 1.00 ~ 0.30

0.00 I~.!~ d 1.00

-~ 1 15 ~ 130 S 2 00

"is 1 lrn ~ 4 00 ~ 4 30 :: 5 00 £! .5 30 < 6 00

6 30 6.50

Obsened elel'ation of the Lake surface in decim:i.ls of a foot.

FT, DEC,

0.000 0 004 0.008 0.016 0,030 0,040 0.053 0,078 0,087 0.089 0.115 0,]30 0.140 0.146 0.143 0.13-1 0.134 0.130 0.116 0.112 0.082 0.066 O.o48 0 040 0.032 0.024 0.030 0,012 0.000

Lunar mean low water.

Moon in the meridian. Lunar mean high water.

{Slightly discrepant, owing to a preponderance of unfavourable winds at this period. Lunar mean low water.

The accompanying profile, marked Fig. t,• shows the mean semi-diurnal tidal wave at Chicago, projected from the foregoing co-ordinates, embracing every vicissitude of winds and weather, &c., which occurred during the whole six months' observations. It shows the altitude of this mean tidal wave to be, at its summit, .146 of a foot, equal to 1¾ inches; and the average time of high­water is thirty minutes after the time of the moon's meridian transit.

On a close examination of all the observations embraced in the series, we find 189 which we think ought to be rejected, because influenced in an extraordinary degree by unfavourable winds. This would reduce the number of observations in the series to 8995; and each co-ordinate of altitude would depend on a mean of 333 observations, and stand as follows, viz. : .

• These are not reprinted, as they can be deduced from the Tables,-ED.

123

TABLE 2.

Showing_ the half-hourly (and in_ t~o places the ~uarter-hourly) co-ordinates of nlhtude of the average sem1•dmrnal lunar tidal wave at Chicago on Lake :Michigan, as derived from 8,99J observations, made between Ja~uary 1st and July 1st, 1859.

Mean 1olar interval of time Observed elevation of before or after the moon's the Lake surface in meridian transit, decimals of a foot.

_H,M, FT, DEC,

~ 5.85 0.000 Lunar mean low water. 5.30 0 005 5.00 0.004 8 4.30 0.013

~ .i 4.00 0.030 0 • 3.30 0.041 0 Q 3.00 0.054 ~; 2.30 0.G78 ,s 2.00 0.090 t 1.30 0.098 ..: 1.00 0.108 ~ .._ 0 30 0.127

0.00 0.148 Moon ill the meridian. -o.so 0.153 Lunar mean high water.

0.45 0.148

~ 1.00 0.137 1.15 0.134 1.30 0,132

s 2.00 0.113

~ -~ 2.30 0.l07 3.00 0.084

s ; 3 30 0.056 4.00 0.040

-5 4.30 0 031 ~ S.00 0.025

"' 5.30 0.023 -< 6.00 0.024

6 30 0.010 .._ 6.50 0.000 Lunar mean low water.

The accompanying profile, marked Fig. 2, shews the character of the mean semi-diurnal tidal wave projected from the modified general result given in the foregoing Table 2. It gives, for its altitude at its summit 0.153 of a foot, equal to t 180/u inch; and thirty minutes after the time of the moon's meridian transit is still indicated as the average time of lunar high water. We would adopt this mean result in preforence to that shown in Table 1, and in the draw­ing ruarked Fig. 1.

From one day before to two days after the periods of the moon's conjunction and opposition to the sun, the observations upon the tide-gauge were made, continuously, both day and night, at regular intervals of fifteen minutes of time apart. This was for the purpose of ascertaining, as near as possible, the time of lunar high water at the period of the spring tides, and also the elevation of the tidal wave at its summit, when influenced by the combined attraction of the sun and moon, acting in the same or nearly in the same direction.

For this object a separate tabulation was made of all the quarter-hourly co­ordinates which occurred from about twelve hours bdore to twenty-four hours after the period of each conjunction and opposition of the sun and moon, from

! ~4 ON A LUNAR TIDAL WAVE IN LAKE MICIIJGAN,

the new moon of JA.nunry 4th to new moon of June 1st, inclusi"c.• In this wn.y we hoped to obtain, at each conjunction and opposition, three semi-diurnnl t ides, each of which would sufficiently approximato in cbara.cter to a semi­diurnal spring tide, and a mean of all would tend to eliminate errors arising from the disturbing forces, caused by irregularities in the strength and courses of the winds.

We were fortunate enough to obtnin good quarter-hourly observations, for as many as twenty-four of these spring tides, as follows, viz. :

At the conjunction of January 4th . . . . , .. . . . 3 tides. opposition of January 18th .... . .. , . . 3 conjunction of February 2nd .•. ..... 3 ,, opposition of February 17th . . .. . . .. 3 ,, conjunction of March 4th. . . . . . . . . . . 3 ,, opposition of March 18th . ... •• . •. . ,. ,, conjunction of April 3rd .. .. ..• . .... None; too stormy. opposition of April 17th . . . . . . . • . • • • 3 tides. conjlmction of May 2nd • • • . . . . • • • . • I opposition of May 16th . , .......... I conjunction of June 1st . . . . . . . . • . . . 3 ,, opposition of June 15th • . .••... .. .• None; too stormy. conjunction of June 30th . ..... . . ... . None; too stormy.

Total .. .. .. .. . ... 24

A direct mean of each quarter-hourly co-ordinate of altitude obtained from these twenty-four observed spring tides, is shown in the following Table 3, and the mean spring tidal wave, projected therefrom, is shown in the accompanying profile, marked Fig. 3. The whole number of observations incorporated in these is 1,200, and each co-ordinate is here derived from a mean of 24 observa-­tions.

Thirty minutes after the time of the moon's meridian transit appears, again, as the time of high water at lunar spring tides, and we have .254 of a foot, equal to 3Tt~ 11 inches, United States measure, as the difference of elevation of the lake surface between high and low water of spring-tides.

\Ve designate, as the establisliment for the port of Chicago, H,M.

¾ foot, 0 30.

It is probable that if the effects of unfavourable winds, and all other disturbing forces which produce irregular oscillations in the elevation of the lake surface, could be fully eliminated, a semi.diurnal lunar tide would be shown, at the periods of the maximum springs, as great as one-third of a foot, or four inches.

The time of low water, and the times of duration of the flood and ebb tides, are given approximately. The extreme rise of the lake tide being so little, and hence the time of the turn from ebb to flood-attended frequently by disturbances of the winds-being often uncertain within half an hour, it can onlv be deter .. mined with precision by menns of numerous observations made at sho;t intervals of time, say three to five minutes apart, from about one hour before to one hour after the turn of the tide from ebb to flood.

• The ~inds were so boi_s!erous, and caused so great perturbations of the Jake surface, at the p~nods of t~e oppos1t1on of ~une 15th, and the conjunction of June 30th, that we were obliged to reJect the observations made at those periods in making up the co .. ordinates of altitude for the spring tides.-J • D. G. '

126

TABLE 3.

Showing the quarter-hourly co-ordinates of altitude of the average semi-diurnal

lunar spring tidal wave at Chicago, on Lake Michigan, as derived from 1,200 observations, made at and near the several periods of conjunction and

opposition of the sun and moon, between January 3rd and June 2nd, 1859.

Meon 1olar interval ol time I Ob,med elevation of before or after the moon's the Lake surface in meridian transit. decimals of afoot.

H.M, FT, DEC,

..- 6.00 0.000 Low water of lunar spring tide. 5.45 0,006 5.80 0,014 6 .15 0,029 5.00 0.035

-~ 4.45 0.042 4.30 0.049

E 4.15 0.057

l 4.00 0.079 3.45 0,081 -~ 8.30 0.089 s 8.16 0.091

i ◄ 8.00 0.101 2.45 0.121

s 2.80 0.129 . 2,15 O,IH ,:i 2 00 0,153 f J.45 0,169 .g 1.30 0,178 ~ 1.15 0,187

1.00 0,195 0.45 0,216 0.30 0,225 0.15 0,226 Moon in the meridian.

0.00 0,233 0.15 0,248 0.30 0.254 High water oflunar spring tide.

0.45 0,241 1.00 0,229 1.15 0,226

~ 1.30 0,221 1.45 0,221

~ 2.00 0,201 J:: 2.16 0.179 § 2.30 0,161 "3 2.45 0,140 -~ 8.00 0.120

3.15 0.112

g 8.30 0,103

0 3.45 0,093

" 4.00 0.072 . 4 15 0.066 { Slightly discrepant, owing to a ,:i 4.30 0,072} preponderai:ice of. unfavour~ble 0 4.45 0.067 winds at this particular period. "' 5.00 0 059 <

5.15 0 046 5.30 O.Q40 { Slightly discrepant, owing to a 5.45 0.042} prepondera~ce of. unfavour~ble 6.00 0.050 winds at tins particular period, 6.15 0.027 6.28 0.000 Low water of 1unar spring tide.

-

126 ON A LUNAR TIDAL WAVE IN LAKE MICUIOAN.

Jn conclusion, we present the foregoing observations as solving n ~robleru which bas been genernlly heretofore denied or do_ubtcd! nnd ns. pro,•10~ the discovery of a semi diurnal lunar tidal wave, of the d1mens1ons herem descnbed, on Lnko Michigan; and hence we infer a similar one on the other great fresh•

water lakes of North America. J . D. GRAHAM, Member of the Society.

PAPER XIV.

NOTES ON THE CONSTRUCTION OF EARTH-WORKS

IN FORTIFICATIONS.

BY MAJOR GALLWEY AND LIEUT. INNES, R.E.

ON THE CONSTRUCTION OF EARTH-WORKS AT FORT ELSON, NEAR GOSPORT,

BY MAJOR GALLWEY, R.E.

The ditch of Fort Elson, which is sunk about 16 feet below the general level of the country, is excavated in the upper strata of the London clay, which consist of red and blueish clays with occasional seams of loamy sand. Portions of this clay become almost liquid when acted upon by water; and in this lies the great difficulty of managing it as earth is ordinarily used in the consti·uction of forts.

The escarp wall at Fort Elson is built "en decharge," as has been explained in Vol. IX of this Series, page 64, by Major Lovell.

The counterscarp was originally formed of earth at a slope of 45°, and is 24 feet high, 16 feet being excavated and 8 feet made; but some slips having occurred, it was reformed at. a slope of¼, leaving a berm of 2 feet at the natural ground line.

During the past year, however, (principally in the winter), the part of the counterscarp facing the south has slipped throughout. The damage done to this face may be partly attributed to the dip of the strata from north to south, which conducts the drainage of the land to the surface of the slope, the other faces of the counterscarp, where the drainage is naturally conducted from the face of the

ON TIIE CONSTRUCTION OF EARTII-WORKS IN FORTIFICATIONS, 127

elope, being uninjured. Judging, however, from the extensive slips which have occurred in railway cuttings in the London clay, and which during the past winter (as I am informed) have cost the London and South Western Railway Company £5,000 in repairs, it is impossible to trnst to any ordinary slope when dealing with this soil, so far as II cuttings" are concerned.

Having formed this opinion some time since, I obtained authority to expend a small sum in the formation. of a concrete facing or revetment, so as to arrive at some remedy for the insecurity of the counterscarp.

A portion of the slope (about 50 feet in length) has been accordingly faced with a shell of concrete to the height of 16 feet, the thickness at top being 2 feet 6 inches, and at bottom 3 feet 6 inches. The foundation, which is 3 feet in depth, projects 4 feet beyond the foot of the slope, so as to afford a good resistance to the thrust in the direction of the face of the slope. The earth was also benched in two or three places to counteract the tendency to slide, and weep-holes were formed by laying drain-pipes 2 inches in diameter in the concrete as the work proceeded.

The concrete was composed of one part of blue lias lime, finely ground, and six parts of shingle from Stokes Bay, and was formed in layers one foot thick, and brought to the profile by means of flat rammers. The face was left rough, in order to test the work as much as possible, but it will always be advisable to

protect such scarps by rendering them with stiff gritty mortar. More than a year has elapsed since this experiment was made, and although

the countersca.rp on either side of it has slipped, the part supported by the concrete facing remains standing, and appears perfectly sound and firm; and as there was an unusual amount of rain during last spring and summer, followed by a winter of great severity, the method adopted for securing the counterscarp may be considered successful.

I have lately noticed the mode generaUy adopted on the London and South Western Railway in repairing slips in cuttings. The toe of the slope is strengthened by throwing in large masses of rubble chalk well packed; and vertical drains, about 4. feet deep and 3 feet wide, are also cut in the direction of the slope, about 20 or 30 feet apart. Tbis seems a good method, and is econo• mical where chalk can be obtaim:d readily.

A great source of weakness in the slopes of cuttings is the usual drain that is made at the foot of the slope, which, being always saturated with moisture, presents no resistance to the tendency to slide. A drain along the centre of the road to receive the drainage of both slopes would be preferable.

The formation of parapets in the upper beds of the London clay requires much care in consolidating the mass, by ramming the earth in layers about one foot thick, and using green brushwood, gorse, &c., in forming the slopes, which should not be at a less angle than! or¾ where space can be afforded. The slopPs of the parapets at Fort Elson are all at 45°, and have given considerable trouble, owing principally to the shrinking of the clay in dry weather and its swelling or expansion after wet, which renders it quite impossible to build on it such works as interior revetments or curbs for racers, ,vith ordinary founda­tions. 'fhe expense magazines in the traverses on the terreplein lrnd in conse­quence to be built on a grillage of timber supported on piles driven 3 feet below the natural level of the ground.

128 ON THE CONSTRUCTION OF EARTH-WORKS JN FORTIFICATIONS,

The ordinary hurdle, which is made of two sizes, generally 6' 6'' X 31 nnd 8' x S' 6", will be found of great assistance in the formation of slopes. Care should be taken to procure them green, so as to give the parapets the longest possible time to consolidate before the decay of the brushwood of which they are mode.

A trial wus made of these in the formation of the exterior slope of the cavalier in Fort Elson, which is inclined at ! and has a vertical height of 26 feet. Continuous rows of the 8-feet hurdles were laid O header and stretcher" at vertical intervals of 5 feet, the outer edges projecting 3 inches to receive the flut sodding.

The hurdles were inclined inwards at an angle of about 20° or 2.5°, so as to afford a good resistance to the thrust of the earth.

It is now more than eighteen months since the earthwork of the cavalier has been completed, and there has been no appearance of a slip.

Hurdles are also useful for strengthening interior revetments, cheeks of em­brasures, slopes of traverses, ana other works generally built with sod work.

The cost of hurdles delivered on the works at Gosport is Ss. a dozen for the smaller size, and lls. for the larger.

NOTES ON THE EXTERIOR SLOPES OF FORTIFICATIONS AT DOVER,

BY LIEUTENANT INNES, R.E.

It has been usual in constructing fortifications to assume that the natural angle of the soil is 45°, and to give the exterior slopes that inclination. In chalk countries, however, the natural angle of the soil is not much more than 34.0 , and to make it stand at the steeper angle it becomes necessary to ram it carefully, to sod the exterior, and to put numerous horizontal layers of brush­wood into all long slopes. These precautions add a good deal to the cost, and even with them serious slips often occur; whilst in slopes formed at the natural angle, as in railway embankments, they are very rare, although the earth is merely shot out of the carts.

It also seems certain that under fire all exterior slopes would be brought down to the natural angle of the soil of which they are made, and it would therefore seem best to construct all such slopes at this natural angle, as determined by experiment, instead of at an uniform angle of 45°.

The only disadvantage is the loss of interior space, but this would be compen­sated by greater stability and a considerable saving of money.

I am info1med that in the embankments on the new line of railway between Dover and Chatham the chalk stands at slopes varying from t to i, and the clay at a slope of about l,

129

PAPER XV.

THE PRACTICAL DETAILS OF PHOTO-ZINCOGRAPHY, AS APPLIED AT THE

ORDNANCE SURVEY OFFICE, SOUTHAMPTON, FOR THE PRODUCTION

AND i\!ULTIPLICATION OF FACSIMILES OF ANCIENT MANUSCRIPTS,

:MAPS, AND LINE ENGRAVINGS.

BY COL. SIR HENRY JAMES, R.E., F.R.S.,M.R.I.A.

By the term photo-zincography is meant, as the name implies, the art of pro~ ducing a photographic facsimile of any subject, such as a manuscript, a map, or line engraving, and transferring the photograph to zinc, thereby obtaining the power of multiplying copies in the same manner as is done from a drawing on a lithographic stone, or on a zinc plate.

The first part of the process concerns the production of a negative photograph on glass of the document, of exactly the same size as the original. This is obtained by the ordinary wet collodion process, and too great care cannot be taken to obtain one as perfect as possible, as every defect will be transmitted through each step of the process till it affects the final result. As affecting success at this stage, the lens used should be as perfect as possible, and fully capable of projecting an image of the size required without sensible distortion. Lenses are used at the Ordnance Survey Office of various diameters, depending on the size of the document to be copied-the largest being 8 inches in diameter, 41 inches in principal focal length, and capable of producing negatives free from sensible distortion 16 inches square, a stop I inch in diameter being placed 8 inches in front of it.

The distance from the lens to the ground-glass of the camera, when adjusted so as to copy a subject to the same size, is 7 feet 3 inches, and from the lens to the subject of course the same.

The readiest means of adjusting the camera and lens in their proper position relatively to the object and to each other, when it is required to produce a negatiYe the same size, is to ascertain by actual mensurement with a proper scale a lineal dimension of the subject (as its width or length), and so to regulate the distance of the lens from it, that when the image is focussed on the ground-glass it shall equal, in its corresponding dimension, that already read on the scale. This can easily be done by a system of repeated trial and correction of error. "'hen the lens and camera are in adjustment, the glass plate is covered ,rith the sensitive coating-exposed, deYeloped, and fixed in the ordinary way; when fixed it is immersed in a saturated solution of chloride of mercury ( corrosiYe sublimate). ,rhen well whitened by the action of the salt, it is removed, washed with water, and then with a solution of hydrosulphate of ammonia, consisting of ten parts of water to one of hyclrosu1pho.te of ammonia of commerce.

R

130 ON THE PRACTICAL DETAILS OF PIIOTO-ZIKCOGRAPHY,

Iu this manner the ground of the negative is rendered extremely dense, without affecting the clearness of the detail. When dried and varnished it i, 1·endy for use.

" ' e now come to the preparation of the sensitive paper. The quality of the paper used is a. point of much importance. Various samples have been tried, but that which has been found best suited for the pID·pose is a semi-transparent kind, with a smooth sw·face, known by the name of engrn:vers' tracing paper.

A solution of gum arabic, or gelatine, is prepared by dissolving three parts by weight of gum arnbic in four parts of distilled water. We generally use gum, but the gelatine takes a stronger hold of the paper.

Boiling water is then satw·ated with bichromate of potassa, and eight parts of the solution of gum arabic, or gelatine, is mixed with ten parts of the solution of bichromate of potassa, both being kept nt a temperature of about 100°.

The paper is evenly coated with the hot mixture with a flnt camel-hair brush, and dried. It iJi then exposed under the negative in the usual way. The time required for printing may be said to vary from ten minutes in diffused light, to two minutes in the sunlight, though there ru-e days on which an exposure of twenty minutes would not impress a sufficiently marked . image ; but at such times it is not advisable to print if it can be avoided, as the results will hardly be good. The period of exposure is determined by the appearance of the print: when all the detail appears distinct it should be 1·emoved.

The next step of the process is the coating of the whole surface of the print with an even and thin layer of a greasy ink, which is composed of the following ingredients :-

Middle LillBeed Oil Varnish .............. .. Wax .... , .. , ...... . ..••••...... .... . ... Tallow .............. , .. .. ............. .. Venice Tw·pentine . . .. .. ..•.•••• .. ........ GUDl 1"Iastic . . .............. . .... ... ... . Lamp Black .. .. .... , ............ , ... . . .

4½ oz. 4 oz. ½ oz. ½ oz. ¼ oz.

3} oz.

A portion of the above is dissolved in oil of turpentine, so ns to make a solu­tion of the consistency of thin cream, which is easily applied to the surface of the print with a brush.

It should here be obsen-ed that the extent to which the greasy ink is diluted is, in a great measure, determined by the natw-e of the subject photographed; if it is of an open nature, such as a bold engraving or etching, the solution may be considerably thicker than when the subject is finer. Experience is the only guide in determining this point.

The turpentine is allowed to evaporate for half an hour, and the print is then floated, back downwards, on hot water for a few minutes, and then removed and laid fnce upwards on a porcelain slab.

T~e surfa~e is gently rubbed with a sponge dipped in warm gum water, and t~e mk r~a~y leaves the s~·face at those parts which have been unacted on by light, while it adheres tenac10usly to the detail.

As soon as the lines are quite clear the print is placed in a flat dish and washed first with warm, and finally with cold water. When ch·y it is ready f0r transferring to zinc or stone. '

ON TH£ PRACTICAL DETAILS OF PIIOTO~ZINCOORAPHY. 131

There are two methods of tra.nsferdng to zinc, varying according to the quantity of ink on the photograph.

If a very small quantity hns been applied on account of the closeness of the subject, the print is transferred by the "Anastatic" process.

For this purpose the surface of the zinc plate is polished with emery powder, nnd made as smooth as possible. The print is placed, for about ten minutes, between sheets of paper which ha,e been damped na uniformly as possible with a mixture of nitric acid and water, in the proportion of fl.Ye parts of water to one of concentrated acid. A sheet of paper clnmped with the acid is laid on the zinc plate, and both are passed between the cylinders of a copper-plate printing press, and the acid being forced on to the zinc, slightly etches the surface. The paper ia then taken off, and the film of nitrate of zinc formed on the plate is carefully cleared off with a handful of blotting paper. The print is next laid on it face downwards, and both are passed once through the press. The paper is then pulled off, and the trausfer is gununed and brought up by going lightly over the surface with a sponge dipped in printing ink softened with olive oil. As soon as all the detail appears strong, it is etched with a ,ery weak solution of phosphoric acid in gum water, the strength of the acid solution being so regulated that a drop placed on a smooth plate for three minutes slightly tints or dulls the polish. The transfer is then ready for printing in the usual way.

If a larger quantity of ink has been applied, the mode of transferring is somewhat different. The plate is prepared by rubbing the surface with fine sand and water, and a zinc mullar, to give it a grained surface. The print is laid, for ten minutes, between sheets of paper damped as uniformly as possible with water; it is then laid face downwards on the plate covered with two or three sheets of paper, and passed once through an ordinary lithographic press. 'l'he sheets of paper being removed, it is damped at the back with gum water, till its adhesion to the plate is so lessened that it can easily be pulled off. After the transfer has been gummed, brought up, and etched as in the Anastatic process, the ink is cleared off with turpentine, and the design is rolled up, with printing ink. Impressions can then be taken from it. The photographic print ca.n be transferred to stone in the same manner as to grained zinc, the surface of the stone being prepared as for ordinary lithographic transfers.

Haying described the methods of transfer, it is necessary to treat further of the considerations which determine the quantity of the ink used, and conse­quently the mode of transfer.

The quantity of ink which it is necessary to apply to the photograph, to make a successful transfer to grained zinc, is greater than that which is necessru·y for stone, and the Anastatic process requires the least of all.

The action of the warm water, in Yi·hich the print is immersed, on the insoluble gum, is to cause it to swell, and the iuk which overlies the lines formed of insoluble gum expands likewise. It is evident, therefore, that if the subject photographed is of a close nature, as a fine engraving, the amount of enlarge­ment of the ink lines may be sufficient to bring them into contact while the print is in the water, and when once they have coalesced they will not again separate when the gum resumes its natural size, on the drying of the print, and there will be a continuous shade of ink instead of lines. In such a case, the quantity of ink applied should be as small as possible, and to enable a light but

132 ON TIIE PRACTICAL DETAILS OF PIIOTO·ZINCOGRAPll\".

even coating to be lnid on, it must also be thin; nnd, ns a consequence of the small quantity of ink used, the transfer must be effected on a smo~th plate, by the Annstntic process, because to make n successful transfer to a grallled plate or to stone, a larger quantity of ink is necessary. .

On the othei· hnnd, as impressions taken from n grained plate or from stone are, as n rule, better than those from a smooth plate, and as a larger number can moreoYer be struck off-if the subject photographed is so open that there does not appear to be any likelihood of the lines coalescing in the w~ter-it ~s be_tter to apply the ink in a greater quantity to the print, as a certam qmmtity 1s a ~in, qua non for the employment of the latter mode of transfer.

PAPER XVI.

ACCOUNT OF THE MANUFACTURE OF A NEW CEMENT,

INVENTED BY CAPTAIN H. SCOTT, R.E.

L1 the 6th Vol. of the Professional Papers, New Series, a short accowit is given of a new cement, and of the experiments which led to its discovery. Since that ,,olume was published, this cement, and a modification of it for internal pl:lstering, have been successfully employed in several of the works executed by the War Depnrtment, and the manufacture of both kinds has been commenced in diffcTent parts of this country.

The processes for making them having been patented the right of working the processes in the British Isles has fallen exclusively into the hnnd.s of private firms, but it had been considered that they might also be employed in the colonies, where no barrier exists to their free use; and in cases when the works which an officer has to carry out are of sufficient magnitude or importance to justify the expense of the means for commencing the manufacture, the following description of the nature and mode of preparing the cement and plaster may prove useful. It will likewise, it is hoped, afford to officers employing them in the prepared state at home, that infol'lnation which the inventor is now frequently 1·equested to supply.

0~ TIIE MANUFACTURE OF A NEW CEMENT. 133

PRELL\IINARY REMARKS,

1. "rhen pure 1imo ~ moUitcned wit~ water it slakes with violence, eYolving great heat and crumbling to a soft white bulky powder. This is a h:rdrate of limo containing nearly¼ of its weight of water which has been solidifi~cl The incr~ased bulk ~ so_ g~eat as in some instances to treble its Yolume, but in pro• portion as the lime 1s impure from the p1·escnce of clay the increase of yolume is notably less.

2. It is a common opinion among builders that the hardest and densest lime­stones yield the strongest and most durable mortars, and at first sight such a supposition seems 1·easonable, but when it is stated that the increase in volwne of the pure and dense limes from slaking exceeds that of the pm·e and porous limes, nnd that they both fall into an impalpable powder of similar quality, when moistened with a suitable quantity of water, it can be readily understood that this opinion may be fallacious, as indeed it really is; what, however, is correct with respect to limes ,vhich slake with great heat to a bulky powder, is quite true, as a general rule, of cements, which set without these phenomena.

3. The invention, which is the subject of this paper, consists in submitting quick lime, heated to a very feeble glow, to the action of sulphurous acid; and the effect on it is to preYent its slaking to a powder, and to cause it to set as cement without notable increase of volume. The original density of the limestone does therefore, in this case also, affect the strength of the cement prepared from it.

4. Pu.re lime is soluble in water, and always remains so, unless reconverted into a carbonate by the action of the air; and in proportion as the mortar made with it is more porous, the soh-ent action of the water affects it more rapidly. It is manifest, therefore, that a process which prevents the great porosity arising from the increase of bulk in the lime on slaking, will cause the solYent action of the water to be slower. This is the chief advantage which the process bestows on such lime if employed in water, but, ns it will be seen from what follows, this advantage carries with it very important consequences, and will enable hydraulic cements to be made from materials with which, otherwise, little could be done with certainty, excepting at a great expense.

5. No limestones will yield limes baying hydraulic properties unless they contain a proportion of clay intimately mixed through them•. The action of the clay varies according to its chemical composition and physical condition, but no limestones will yield limes which can be said to be eminently hydraulic unless they contain 20 per cent. of clay and upwards; and according as the quantity of clay is smaller, so more and more of the mass will remain soluble; and thus more and more of the lime which would become insoluble, if time were giyen it, through a chemical combination ,Tith the clay, is also dissoh-ed out. The sulphur process, therefore, ns it delays the solution of the pure limes, will, in the case of limes naturally mixed with clay (by the density which it imparts to their mortars), not only retard the action of water upon the mass generally, but will give time for the clay to combine with all the lime which it has the power of taking up, before the water can dissolve much of the latter. l\1any

• See Appendix II, III, and IV.

134 ON THE MANUFACTURE OF A NEW CEMENT,

limes, however, which contain only 20 per cent of clny will yield hydraulic cement; and some will yield hydraulic limes if burned at a low temperature, but hydraulic cements if the tempcratw·e of burning is raised.

6. It is well known that burnt clay, brick dust, metallic slags, and substances of a like nature gi,·e more strength to both pw·c and feebly hydraulic lime mortar, but they will not often render them insoluble with sufficient rapidity to resist the solvent action of water, if immersed in a pasty state. Fl'Om the greater quickness, however, with ,vhich limes set after they have undergone the sulphur process, and also from the greater density in the mortars made from them when thus converted into cements, time is given for the indurating action between the lime and the clay to take place before the water has seriously damaged or disintegrated the mixture. The advantages of the process are therefore equally great, whether applied to limes naturally hydraulic, or to those which it is desired to make so by the addition of burnt clays.

7. Though the tendency of limes to slake to a powder with heat is very much reduced by the effect of the sulphurous acid (paragraph 3), it is not destroyed. 1st. The moisture of the air ,rill gradually affect and · spoil them, and though more slowly, will produce in them the same phenomena as in the unprepared limes. The injury so caused is less in degree, and makes slower progress, with the hydraulic than with the pure limes. 2nd. The phenomena attending ordinary slaking will be produced in the cements prep8l'ed from the pme and slightly hydraulic limes, if allowed to remain in large heaps after they have been made into mortar. Heat is gradually generated under such circumstances, and a return to the condition of ordinary lime is thus brought about. 3rd. 'fhe phenomena of ordinary slaking occur when the cements from the pure and slightly hydraulic limes are applied as mortar to dry absorbent surfaces. The mortar is thereby drained of its water before the combination of the cement and its equivalent of water is complete, and, instead of solidifying, the mortar crumbles to a powder.

8. Sir Charles Pasley, in his valuable treatise on limes, calcareous cements, &c., remarks: "I haYe no doubt that the blue lias lime would unite stones together nearly tls powerfully as the best cements are capable of doing, if it did not sweU in all directions when the attempt is made to combine the two processes of slaking and setting, which take place simultaneously in cements, without increase of bulk, and consequently without forcing them to split or detach them• selYes from stones or bricks." The results obtained have demonstrated the correctness of Sir Charles Pasley's opinion with respect to the lins lime, and have shown that the principle involved in his remark holds good more widely than he has expressed. The pure limes that he characterizes as " only better than none," when they have been subjected to the action of the sulphur fumes slake and set simultaneously, and are converted into cements adapted for a...; situations, and, by mixture with calcined clays, into hydraulic cements. The feebly or slightly hydraulic limes, which in their ordinary condition are suitable for dry walls, are in the same manner converted into cements fit for wet situa• tions, and, by mixtw·e with calcined clays, into excellent hydraulic cements. Both the hydraulic and eminently hydraulic limes, which in their natural state are fit for water works, are thus converted into cements, which are superior to all the water cements excepting only Portland of the best description.

ON THE MANUFACTURE OF A NEW CElllE!IT. 135

9. These cements are adapted for inside and outside work ns well as for masonry nod concrete. Since howeYer there is more labour requll'ed to trowel them to a fine face for papering and painting than in trowelling the ordinary lime and hnir "fine stuff;' it is better, excepting where great hardness is required, to employ a modification of them for this purpose. The plaste1·er finds them what he terms "fiery" under the trowel, that is not sufficiently plastic and retenth•e of water. When chalk can be had this can be ground down with the cements to supply the qualities wanting, or, in the absence of chalk, some of the snme sort of lime as is used in the manufacture of the cement may be slaked to a powder and mixed in with it. To distinguish such mixtures from the cements, they have been termed "plasters" in the trade, and are so termed also in the following description of their manufacture.

PREPARATION OF THI'.: CEMENT.

10. The limestone to be employed in the manufacture of the cement is burned to quick-lime by nny of the ordinary processes, avoiding over-burning as usual. Limes burned until they assume a blue or greenish tinge require peculiar and Yery careful treatment to fit them for the purpose.

11. The quick-lime is either wheeled in barrows or carried in baskets into an oven of the form shown in the accompanying plan, and is laid on the perforated arches, forming the floor, to the depth of 1 ft. 6 in. on the crown, and 2 ft. OYer the haunches. V/ith large sized lime this depth may increase a few inches, and whC'n the lime is very small it must be somewhat decreased; or in other words, the lime must not be so closely and deeply packed as to impede the draught too much. The lime dust produced in burning the lime becomes useful in making the hatches of the oven air-tight, and if there is any excess it may be ground down with the cement without sensibly deteriorating its strength.

12. When the oYen is loaded, the charging hatch is closed with a double 4-in. dry brick wal1, the included space being filled in with lime dust. The whole may be made air-tight at top by means of the opening (see Plan) through the crown of the arch. Iron doors can be employed, and with a saving of labour, but the brick wall will generally be found more convenient.

13. The small hatch, intended to assist in cooling the oven in order to draw the charge, is better closed with an iron door on hinges, the whole being made tight with a mixture of moistened clay and sand technically termed " pug."

14. If the lime employed is pure or feebly hydraulic lime, it is ad,~sable to allow it to remain with a current of air passing through it for a period which will vary, generally, with the temperature of the air and the draught through the o,•en. The object of this is that the moisture carried through by the air may open or split the lime a little, and otherwise facilitate the combination of the sulphurous acid during the subsequent process, without, however, causing it to fall abroad. Whatever the nature of the lime operated upon, such exposure renders the process more certain, and should be employed whenever the tendency to slake with heat is not readily destroyed without it. The period of exposure will vary from 12 to 48 hours.

136 ON THE MANUFACTURE OF A NEW CEMENT,

15. After this exposurr, n fire of coke or coal is kindled by means of a faggot of brushwood on the fu·e bars, and a slo,v fu·e is kept up tmtil the lime imme­diately over the arches shows a dull glow, such ns is barely visible when viewed in the dark through the pipes shown in the side of the oven. The firing is then raked out, and after the lapse of a quarter or half nu hour, according to the size of the oven, the nsh-pit is closed, and the chimney top coYercd with a slate stone, or plate of iron, until it is judged that the heat throughout the mass of lime is pretty well equalized. 'When coal is used, there is sometimes a little difficulty in preventing the smoke escaping tlu:ough the fire doors after each fresh feeding of the fire, but this may be obviated with a little care and more frequent feeding. The flame of the coal heats the charge more equally. A mixture of coal and coke may also be employed.

16. The time required for heating the lime depends on so many circumstances, as the size and charge of the kiln, the closeness with which the lime is packed, the nature of the fuel, the draught, &c., that it is scarcely possible to say before­hand how long it will take. The same remark applies to the equalizing of the temperature in the charge. The production, however, of the dullest possible glow, as above explained, will sufficiently indicate when the first point is attained1 and after the burner has made himself acquainted with the action of his o,,en, the amount of fuel expended, together with the time occupied, will prove a sufficient guide without the use of the viewing-pipe at all. He will soon learn, also, the time he should allow for the equalization of the tempera­tm·e. Neither point requh·es great nicety. These instructions have in several cases enabled manufactm·ers to make the cement without ful'ther assistance.

17. 1Vhen the heat in the oven is judged sufficient, and to be sufficiently equalized, the ash-pit and chimneys are opened, and iron pots containing coarse unpurified 11; sulphur are pushed in on the fire bars, and placed in a manner to distribute the fumes of the burning sulphur equally. The pots may be made of wrought iron, of sufficient capacity to hold about 25 lbs. of sulphur each, the allowance being 15 lbs. to each yard of lime. A few red hot cinders are thrown into each pot as it is pushed in, to ignite the sulphur. In 10 or 15 minutes, the sulphur will be fully ignited, and its fumes will begin to escape through the chimneys yery freely; the chimneys should then be closed again perfectly, using a little clay or lime dust to make the cover tight. The fire doors and ash-pits are also to be plastered at the crevices, with the exception of a small opening at the bottom of each of the latter, which opening is to be regulated by the amount of air which may be required to continue the combustion of the sulphur without allowing the sulphurous acid fumes to escape; and such escape is at once detected by the smell.

18. When the sulphm· is all consumed, which may be ascertained by looking into the oven fire door from time to time after some hours ha.Yo elapsed, the wall closing the charg~g hatch is thrown down, and all ot~er openings made free to the passage of air, to cool the charge and oven sufficiently to allow the former to be removed.

19. The grinding is then commenced; a few trial samples are made up with water, and an examination made at the top, middle, and bottom of the char!!e, to obtain information as to temperature for future guidance. If the lime fr~m

• See Appendix V.

ON TJIE MANUFACTURE OF A NEW CEMENT. 137

the bottom of the charge when moistened remains quite dead on the outside of the lumps, a sort of crust• having being formed there, and at the heart of the lumps retains its usual properties, this is n. proof that the bottom portion, if not the whole charge, was too hot when the sulphur process was commenced; if the upper layers still retain the usual characteristics of the unpreparecl lime, no crust being Yisible on the bottom portions, this shows that the he<Yt at the top was not great enough, nnd probably that the temperature tluoughout was too low. Some 11icccs will always be fonnd insufficiently prepared, but their effect is lost in the mass, nnd the samples should be three or four in number from each part of the charge, top, bottom, and centre-, avoiding a selection of pieces near the walls. If, in any case, the mass is fo1md insufficiently prepared, and the lower layers are crusted, the upper half may be removed and employed as ordinary lime, and the lower half be ground down ns cement. If the process should be judgl·d to have brC'n quite ineffectual, the removed portion of the charge can be replaced with fresh lime, and the operations of heating the lime to a faint glow, nnd of burning sulphur under it, be repeated; with ordinary care, howeYer, a. failuret can hardly occur, and should the s:unple specimens set firmly "in pats," 6 inchrs square and ,tau inch thick, but yet grow too hot in setting to be safely trusted in work, a few days exposure on the floor of a shed will render the cement fit for use. It is better however that '' in pats" of the above size, made up with water to a stiff consistency, and without admixture of sand, the warmth in setting, even when the cement is quite fresh from the oven, should be barely perceptible.

20. The grinding of the cement is the most serious part of the manufacture. Should the extent of the works justify a considerable outlay in grinding apparatus, the flour millt construction is to be preferred, horizontal crushing rollers being used to reduce the lumps of cement to a size which the eye of the runner mill stone can readily take. It is better also to sift it through a sieYe, the coarse particles being again passed through the stones. For grinding on the small scale, a pair of Yertical wheels of iron or stone, turning on a pivot between them by horse power must be resorted to, the sifting apparatus being either attached by suitable machinery to the gearing of the wheel, or worked by manual labour. The wire gauze used for the sieYes should have 30 meshes to the inch. 'l'he construction of both description of mills is well understood by mill-makers.

21. When the cement is prepared from the pure and feebly hydraulic limes and it becomes necessary to impart to them properties which will enable them to resist the action of water, artificial or natw·al puzzuolanas must be resorted to. If such substances are ground down with the cement to a fine powder, and intimately mbred with the cement, 1 part of puzzuolana§ will giYe to 2 parts of pw·e lime cement, by weight, the necessary degree of resistance, but if mi...··d11r0

by hand labour is alone aYailable, nnd the puzzuolana is not in a fine state of division, its quantity in proportion to the cement should be increased, the amount of sand used for the mortar being correspondingly diminished.

• See Appendix VI. t See Appendix VII. t See Appendix YIII.

§ See Appendix IJ, III, and IV.

138 ON THE MANUFACTURE OF A NEW CEMENT.

22. The clays best adapted for the manufacture of artificial puzzuolnna arc such as nre greasy to the touch. The temperature at which they ought to be calcined depends upon thell' chemical composition, but the action of tl1e consti­tuents is complicated, and actual trial must be resorted to for the determination of the most efficient clegree of calcination. To make the trial, a portion of the clay under examination nfay be moulcled into a cylinder 5 or 6 inches long nn<l 1¼ inches in diameter, or thereabouts. This cylinder, when dried, is to be exposed, the one end in a violent fire, the other on, or near, the outside of it. "rhen the more highly heated end begins to vitrify, the cylinder is withdrawn from the fire and diYided into three or four portions, according to the general appearance and colour of the different parts. By pulverising each part, and mh.ing this puzzuo~ lana with the cement, in the pro1>ortion of 1 part of burnt clay to 2 or 3 parts of cement, by measure, it is easy to determine by actual trials in water, what degree of calcination gives the best results. To prevent the cylinder from breaking in the fire it is moulded round a wire. As a general rnle it will be fowid that clays containing limes ancl other metallic oxides, especially alkalis, become energetic at low temperatures, though they ma,y also succeed when burned at a '\"iolent heat. The poorer clays will give good results only when calcined at a. "'ery high tempemtw-e, and they have the further disadvantage of being difficult to reduce to a powder.

23. Their calcination on the large scale may be cal1.'ied on in a common lime­kiln, of an inverted cone shape. 'l'he clay is to be made ready for burning by roughly moulding it into rounded balls, of the size of an ap11Ie, which are left to dry in the air. A rather thick layer of coals is placed on the bars at the bottom, and on this a layer of balls of clay, then another layer of coals is placed, and so on, thus filling the kiln with successive layers of fuel and balls of clay. ,Vhen the kiln is about two-thirds full, faggots of wood are to be placed beneath the bars aud lighted, and as the combustible is consumed, new layers of balls and fuel must be supplied. above, '!'he appearance of the clay will at once shew, on removal from the bottom of the kiln, whether sufficient or too much fuel is being used; and since tJ1e withdrawal of the burned clay at the bottom and the addition of fresh clay and fuel at the top may be continuous, the proper propor­tions will soon be ascertained. These remarks on clays apply equally if the burned clays are to be used with ordinary lime. The method of ascertaining the proper degree of calcination for them was employed by l\.I. Courtois, Engineer of the Pants et Chaussees, and that described for burning them on a large scale is recommended by General Treussart, who made much use of such artificial puzzuolanas.

PREPARATION OF THE PLASTER.

24. In the mam1fncture of plaster, if chalk is to be used, the chalk is- first dried in small piec~s in one of the oYens used in preparing the cement, and the cement and the dried chalk• are then ground down in equal proportions. If slaked lime is used, lime of such a nature as will slake to a fine powder is immersed. in water, in pieces of the size of apples, for a few seconds, until bubbles of air no longer rise from it in la1·ge quantities. It is then thro",1 into a heap

• See Appendix IX.

ON THE MANUFACTURE OF A NEW CEMENT. 139

in a con•red place, and there left until tho following day that the slaking may be com.plete. The immersion can be com·eniently effected by means of a. bucket with a. 1Jerforated bottom. The slaked lime is next thrown into a hopper which C'ommu1lieatcs with the sieve of the mill into which the cement passes after leaving the stones, ancl it is allowed to run from the hopper in such quantities as will, in measure, equal the quantity of cement tfil·own from the mill stones in the same period of time. If this mode of procedure is inconYenient, the lime may be sifted, by itself, from the unslakcd portions, and then be mixed with the cement in a revolving clrum furnished with arms, which, by suitable machinery, turn in a contrary direction to the drum; or, after sifting, the slaked limo muy be mixed with the cement in equal measures, by simply turning the two powders oYer and m·er with a shovel until the incorporation of the :ingredients is suffi­dently brought about. The paxticular method of mixing them must depend on the magnitude of the works on which the plaster is to be employed; the first is the most efficient, and for a manufacturer the cheapest; it enables the workmen also to protect themselYes better from the dust and inconYenience which must always be caused where fine and impalpable powders are moved rapidly by manual labour.

26. The prepared cement and plaster are packed either in cases or bags, according to the period that must, or may possibly, elapse before their employ­ment. The cask of course affords the best protection, and is to be employed when the material may remain in store for some time. The cements prepared from limes that are sti·ongly hydraulic may generally be packed in bags with iafcty, as they suffer far less from the action of the atmosphere than when prepared from the pure and feebly hydraulic limes.

26. Before proceeding to the preparation of the cement on a working scale, it is recommended that preliminary experiments be made on the limes available, as it possible that there may be some either not suitable for the process, or so little improved by it as to render its adoption unadvisable. The preceding remarks will l'Cnder such experiments easy, but in constructing a small oven for the purpose, the vertical dimensions given in the drawing of a working OYen must not be reduced in the same proportion as the horizontal. The cxtrados of the lime arch must not be nearer to the fire bars than 3 feet, 01· tlrn lime will Uc unequally heated; nor less than 3 feet below the crown of the soffit of the covering arch, or the result will be uncertain, apparently from insufficiency of air. An oven 4 feet 6 inches long by 2 feet 6 inches wide will suffice, the depth of the layer of lime placed in it not exceeding 9 inches.

INSTRUCTIONS FOR USING THE CEMENTS.

27. The cements are to be kept dry ru1d free from contact with the air (see

parugraphs 7 and 25). . . . . . ::!8. The cements prepared from feebly hydraulic lime, which 1s easily

reduced to a fine powder, will carry more sand than such as arc prepared from pure or eminently hydrn,ulic limes. That "·hich is JJreparcd from the grey chalk lime will make good work with as much as 5 parts of clean washed sand to 1 of cement, but, as a general rule, for cements prepared by the sulphur process, the quantity of sand should not exceed 3 parts of sand to 1 of cement,

HO 0~ Tirn MANUFACTUllE OF A NEW CEMENT.

for brickwork or masonry; 1lparts of sancl to 1 of cement, for plastering. In damp situations the qunntity of sand must be reduced, ancl for mortar to be at once immersed in the state of pnste, it should not exceed 1 ½ of sand to 1 of cement }JOWdcr. ,vhcu artificial and natural puzzuolnnns arc employed, the q1umtity of sand used is not to constitute more than two-thirds of the mortar for damp situations, nor more than one-half for water work. For tide work, when there is a wash of water, these cements m·e not so applicable as the quick setting Harwich and Sheppey cement, or other cement of similar properties.

29. For plastering, the loss by extra labour, in applying a "short" mortar, will probably preycnt more than 4 parts of sand being used, if the sand is clean and sharp; with loamy sand, it would be possible to use a larger proportion of sand ·without much extra lo.hour, but such sand ought not to be employed. The plaster should be laid on in two coat work. :Much more labour is expended in trowelling the cement to a fine smooth sm·face, than in trowelling lime and h air, and therefore for all internal plastering, excepting when great hardness is r equired1 the plaster (prepared as described in paragraphs 10 and 24), should be substituted for it, as before stated. For trowelling, 1 part of sand to 1 or 2 parts of cement should be employed.

30. The surfaces to which the cement is to be applied must be thoroughly wetted beforehand. Its full adhesiYe ·properties are not developed unless the a:;urfaces are Just ceasing to drip, when the mortar is laid on. The work.man will disobey every injunction in this respect if he can do so without detection, and it would probably be a beneficial plan in many cases, if the Engineer in charge of works employed men paid by Government to perform the duty of wetting the bricks before they are laid. The little adhesion found frequently to exist between bricks and morfar, and also the numerous failures of cement coatings and their rapid decay, may generally be attributed to the neglect of that clause of the specification which provides for wetting the materials to which they are applied, but which, unfortunately, cannot provide that the superin­tendent of the work shall be duly impressed with its importance.

31. For concrete, from 6 to 10 measures of ballast to 1 measure of cement powder may be used according to circumstances. In small bulk and in dry situations the cements will stand well with the larger quantity of ballast; for water work, and dam11 sites, the smaller proportion is to be used. The concrete is made and used in the manner practised with ground lime and with Portland cement.

32. Since the cements take some time to set, the workmen will generally endeavour to mix large quantities into mortar at a time; so long however as the mortar can be used up before it commences to warm and set, (which it will do more rapidly as the mortar heap is more bulky), no evil effect follows. The cements made from the pure and feebly hydraulic limes may, if mixed with three or four of sand, remain before being used from 30 minutes to an hour, but the less the proportion of sand the shorter must be the period. The hydraulic limes yield cements which neither warm so readily nor set so quickly a■ the cement made from the purer limes, and they remain for a longer time after being made into mortar without injury. 'fhe quantity of any cement which it is advisable to mix at one time will ma.ke itself appn.nnt in the first day's work.

ON TllE l\L\.NUFACTURE 01:' A :rrnw CEMEX'£, Hl

INSTRUCTIONS FOR USING THE PLASTERS.

33. These are not recommended for external work, unless employed in summer time, and in situations where they are not affected by the moisture which rises from tho ground by capillary action. Thdr chief use is for internal work, when they csn generally be applied more chcnply, and with far more satisfactory results, than lime and hnir.

34. }'or rendering and floating coats on brick and stone walls, 3 parts of sand mny be used to 1 of cement; for the setting coat, equal parts of sand and plaster, or a. less proportion of sand according to the finish required to be given to it; for fine trowelled work, 1 of sand to 2 of plaster may be used. 'l'he use of loamy sand detracts greatly from the strength with which the plaster sets when mixed with clean sharp sand.

35. On lathwork, not more than 2 parts of sand to 1 of plaster are to be employed for the rendering and floating coats; and the usual quantity of hair, is, in this case, to be mixed in with it, or there is a loss in point of labour. The under coats should have set and dried before the finishing coat is applied, or the warping or twisting of the wood will cause the trowelled surface to crack. rrhe plaster will adhere more strongly to walls if they are wetted, but can be used on new work without any special precaution in this way. The rendering or the floating coat must always be wetted before the finishing coat is applied, and it is better, on brickwork, to follow on with the coats as fast as possible.

APPENDIX.

I. The philosophy of the alteration effected in limes by the sulphur process is not understood. The sulphurous acid npparently converts a portion of the lime into sulphite, and this absorbs oxygen and passes into a sulphate. The sulphate of lime, so formed, in some obscure way produces the change; perhaps it does so by transmitting its equivalent of sulphuric acid from one particle of lime to another, until the whole mass has set, particle by particle, as sulphate; but this is mere conjecture. A small quantity of finely powdered plaster of Paris or gypsum (i. e. unburned plaster of Paris, or liydrated sulphate of lime) and some other sulphates, produce similar results when intimately mixed with quick lime; but the mechanical difficulties of making on the large scale intimate mixtures of substances differing greatly in their relative amounts, has hitherto prevented the adoption of this plan for manufacturing the cement. Attention was again directed to the effect of a mechanical mixture of plaster of Paris by Mr. Abel, Chemist to the War Department, who had kindly giYen his assistance in the endeavour to trace the nature of the change in the nction of lime produced by the sulphur process. A trial made by the inventor with plaster of Paris on his first discovery of the change which lime underwent when dully ignited over

142 ON 'flIE MAN UFACTU RE OF A NEW CEMEN'f,

coke or conl hnd not been successful, probably owing to the freshness nnd purily of the lime experimented on, and the idea wns entirely abandoned until o. dis­cussion arose on the possibility of the small quantity of sulphate of lime formed in the process (about 5 or 6 per cent) producing the effect in grcnt measure by its own property of setting when mixed with wnter. This led to further experiments, when, finding from Mr. Abel's experiments that the mechanical addition of plaster of Paris did produce no effect similar in kind to that which resulted from the sulphurous acid, but still impressed with the idea that it could not do so notably, in virtue of its own setting properties, the inventor tried the effect of gypsum and crystallised sulphate of mngnesia, sulphate of iron, &c., which are quite inert in this respect. As these substances produced similar results notwithstanding their entire ,•rnnt of setting prope1·ties, it was evident that the true solution of the phenomenon was not yet found, and the above conjecture has been hazarded.

II. l\I. Vicat's classification of limes, according to the quantity of argillaceous constituents, has been generally rccrived, and has been adopted in this paper (see Vient on Cements, sec. I, cap. 1, Smith's translation). It must, however, be ngardcd as only approximately correct, since their hydraulic energy will vary with the nature of the clay and the temperature at which the stone is burned. In the strongest cement the bases of the clay, ,•iz., alumina, iron, potash, and soda, equal -; the silicic acid by weight. In the best cements the relative pro­portion of the argillaceous to the calcareous constituent is nenrly as 36 to 64, or 24 to 76 in the unburned stone. A larger proportion of clay deteriorates the quality of the cement. If it forms ½ of the whole, the cement is better used as 1mzzuolana (see paragraphs 6, 22, and 23), and when the clay exceeds £ of the whole it will no longer set hard under water without admixture of lime, either in its ordinary state or 11repared by the sulphur process. Such puzzuolanas, however, as contain a large amount of lime must bear a greater proportion to the lime, or the lime converted into cement, with which they arc mixed, than when the puzzuolana contains little or none of that ingredient. The point to be obtained is a due proportion between the argillaceous and calcareous consti­t uents of the mortar, and supposing the clay to be impalpable, and equally disseminated through the lime, the proportion of 36 to 64 is best ; but according as the mixture is imperfect, or the puzzuolana coarse grained, or of poor quality, and therefore not so fit for chemical combination with the lime, its quantity mnst be increased. ,vhen argillaceous limestone, finely powdered, has muriatic acid or nitric acid poured on it, all the lime is dissoh-ed out., and the clay is left as a residue. To determine the amount of this residue accurately, requires a slight knowledge of the manipulations of practical chemistry, but a yery rough experiment will afford an approximate result.

III. Clay, after calcination, especially in contact with lime and other metallic oxides, is more readily attacked by acids; the iron, alumina, &c., with some of the silica, are dissolved, but the mass of the silica affected by the acid remains a transparent jelly-like residue. Heat assists the decomposition.

IV. Impure clays are after calcination the most soluble in muriatic acid and will gener~lly be found preferable for artificial puzzuolanas, because the; become energetic at low temperatures, and therefore require less fuel and also because, being slightly calcined, they are easier to grind. Impure c'iays con-

ON TilE MANUFACTURE OF A NEW CEMENT. 143

taiaing 10 per cent of lime nnd upwards, in some instances at least, become energetic as puzzuolanas when calcined gently,-diminish in their energy as the temperature is raised,-and again recover it when heated to :incipient vitrification.

V. The sri.me effect will he produced by calcining hou pyrites, or other metallic sulphuret, beneath the lime. The cement was first made indeed by the sulphU1·ous acid set free from the combustion of ordinary coal and coke containing a little pyrites, and it could be readily manufactured with coal having a large amount of this impurity.

YI. The action of the sulphurous acid on the lime is perhaps greatly assisted by what is termed sul'face action, for it finds its way readily to the heart of large masses unless the heat is too great, when the combination goes on very rapidly on the outside, and the dense crust thus formed stops the action.

VII. On the first establishment of the manufacture of this cement, Messrs. Lee employed lime burners upon it, but they bad apparently, from their long practice in lime burning at high temperatures, become unable to bring them­sel \"es to work at a lower heat; at first they brought the charges to a bright red heat, and, when that tendency "·as conquered, fancied the lime was hot enough, when no ordinary observer could perceive anything approaching to a glow. A pensioned corporal of Sappers (Corporal A. ,vright) was then employed, and found no difficulty whatever in the matter. The quantity of fuel required to bent the lime must ,,ary with the nature of the fuel, and the size and condition of the oven. At the Messrs. Lee's works they used ¾ of a bushel of coke per yard of lime.

VIII. In the mill at :Messrs. Lee's works, 40 cubic yards of cement, yielding ench 18 imperial bushels, are ground in 8 hours. The cement being prepared from chalk, and burned in a flare lime kiln, is however very soft. In the horse mill, with a cylindrical stone s~t on edge working in a trough, it required, per diem, to g,.·ind and pack 12 casks (conts.ining each 5 bushels), ¼ day of a man and horse to crush the cement, and 1 day of two labourers to sift and cask it. Had it been sifted by a machine turning on an axis, instead of by a sieve having a forwarcl and backward movement, the quantity casked per diem by two men would probably have been much larger.

IX. It is considered probable that the calcareous paste found by Colonel Nelson at Bermuda, and doubtless existing in other coral islands, would serve the purpose of chalk.

APPENDIX X.

Ox TilE CEMENTS MADE IN ENGLAND BY CAPTAIN SCOTT'S PROCESS,

AND ON THEIR PROPERTIES AND USES.

The foregoing description "'ill, it is hoped, enable an officer at a foreign sta~ tion to manufacture and use the cement and plaster without much difficulty. 8ince, however, their action is not similar in all cases, but Yaries with the nature of the lime employed in their manufoctw·e, and the peculiarities resulting_ from those a,·ailable for the pw·posc in this country are now known from experience,

144 ON Tirn MANUFACTURE OF A NEW CEMENT.

more precision can be given to the instructions for nsing them than when the nature of the lime is unknown, and may possibly yield cements of very different characters. In the latter case only such general inst.ructions could be given as nnalo"'y rendered of probable npplicntion, but, for this country it will now be attem;ted both to lny down precise rules for guidance in their use, and for judging whether the material supplied by the manufactw·cr i: ?f pro11er _quality and in proper condition. Although it may lend to some repetition, thesc mstruc­tions will be sufficiently complete to obviate the necessity for making reference to what has preceded when seeking information only on the manner of using the cement and plaster in Great Britain and Ireland.

The chamcter of the cements I)repnrecl from different limestones Yarics with their chemical constitution and physical nature. " 'ithin certain limits it improves with the amount of clay which it naturally contains, but the results are influenced also by the quality of the clay and by the density of the stone. In this country the Lias limes have given the best results, and the marly chalks follow, those being most suitable for the pw·pose which contain from 10 to 25 per cent of clay. In Ireland, the "'est of England, South \Vales, and the Midland Counties, the Lias should be specified as the lime to be used in the manufactw·e; and in the neighbourhood of London , and on the South-East Coast, the marl chalks. In every case it would be advisable to state the amount of argillaceous constituents which the cement is to contain, and by reference to the Su1Jerintendent of the Chemical Branch of the " 'ar Department it can always be determined whether the specification is bciug complied ,Tith in this r espect. For London, Chatham, and Dover, two qualities can be had. The one (B) containing from 8 to 12 per cent of argillaceous constituents, which is yery suitable for all dry work. The other (A), containing from 18 to 24 per cent, which is the better of the two for pointing, for external stucco, for foundations, damp and rnassiYe masonry, and for hydraulic purposes generally. Notwith­standing its superiority, this has not been much used, because with the pres.ent arrangements of the manufactw·ers (Messrs. Lee, Son, and Smith, of Halling) its employment is attended with a trifling extra expense, which, however, would disappear with a fall' demand.

The Messrs. Rickman and Co., of Lewes, rnanufactw·e from a chalk, which, for hydraulic purposes, yields a cement intermediate between the above two qualities, and this is the cement which is now supplied to the South-East Coast, Portsmouth, and Gosport, It should not contain less than 15 per cent of argil­laceous constituents. The cements made from Lias lime should contain upwards of 18 or 20 per cent. To assist in conveying an idea of the peculiarities and salient features of the cements made by the process, the results of the com­parative experiments which have been tried wit.h them will now be given. The earliest of these, included in Tables I to VlII, were made at Chatham by Corporal Grey, R.E., under the direction of Captain Schaw, R.E., and on his temporarily quitting the R.E. Establishment, under that of Lieut. 1\foncrief, I.E., and of the inventor. The whole of the cements, and the Lias lime experimented on in this series, were sent by the manufacturers with the knowledge of the use intended to be made of them, and it is therefore to be }>resumed that they were all at least of fair quality. The Scott's cement was of the description (B) con­taining from 8 to 12 per cent of argillaceous constituents, prepared by Messrs.

ON Tll"E MANUFACTURE OF A NEW CEMENT.

Lee. The bricks employed were ordinary stocks, all rubbecl to the same dimensions at their smaller ends, by which they were united in pairs, the area of the joint being made 4 inches by 2:h and its thickness about one-fifth of an inch. The mortar was worked to the same consistence in all cases excepting in the fu·st half of the experiments made with Scott's cement, without sand, and with 1 part of sand to 1 of cement, when the mortar was very fluid an(l the joint thereby somewhat weakened. The pairs of bricks were pulled asunder by weights; and in some instances the mortar separated cleanly from the brick, but more frequently the .fracture occm-rcd through the morb:u·, whatever the nahu·e of the cement experimented on. The force of adhesion to the brick, however, as compared with that of the cohesion of the pa.rticles of mortar, was less as the quantity of sand in it was lnrgcr. ,vhen cementecl together, the pairs were arranged on the ground in rows under the cover of a shed open at the ends; the weather was warm and dry, the experiments having been com­menced in the June of 1857; the sand was clean, of good size and sharp; and the bricks were invariably wetted thoroughly before they were cemented together.

TABLE I.

Showing the weight in lbs. which fractured the joint after 11 days from the

date of its being made:-

COllPOSl'l'IO?I' OF l\lonTA.R.

REMARKS, NAIIBOF Cu:Ell'l', 0 11and, 1 l sand. 2eand. 8 s:iod. 4 11aud. 5 sand. 6 sand 1 cemt. l cemt. 2 cemt. 3 cemt. 4. cemt. 5 cemt. 6 cemt.

f----+---------1

Messrs.White'::; } ... 504 Portland. Messu. Lee's l ··· 701 Portland. Medina ... 400 352

Roman. ... 400 279

Atkinson's •. 385

Bath •..•• 261

Lias Lime. , 119 80 Messrs. Lee's l 292 ~cott's cement 286

ll quality .. j

433

533

278

178

115

135

124

308

303

201

154

79

128

29

328

420

149

149

49

Si

281

238

83

73

4•2 ··{ 19-1 18}

With 0 sand, the bricks geni;rally broke fir::.t,

Do. With 5 and G sand only 4 trials. "iih 6 sand, the joint broke with weight of scale equal to 23 lbs.

""ith G of sand, the j oints broke in handliug.

N, B.-The numbers ai·e means of trials rnryiug from 5 to lJ in number.

T

-,

146 ON THE MANUFACTURE OF A i;EW CF.:!.IENT.

TABLE I I.

Showing the weight in lbs. which produced fracture after the joint had been

made 30 clays :-

CoMl'OIITIOI' OP Mon.us.

N A.YJ: OP CBlfBN'l', Osand. laand . 2 &and . 3 sand. 4sand. 5 sand. 6 sand. RU1All.K8.

lcemt, lcemt. l cemt. lcemt, lcemt. lcemt, lcemt.

White's Port- } ... 365{ With O and 1 sand, ... 667 505 521 356 the bricks gene-

land , , •. rally broke first. Roman •••• 499 424 236 ... . .. ... . .. Medina, • , • 512 538 370 ... ... ... ... Lias .•... • 124 ... ... ... ... ... ... Scott's B qua-

jm 527 lity .•.•. 514 528 331 398 317

N.B.-The numbers given are the means of 5 trials.

.. A very extens1"fe series of experiments on bricks JOmed together ns above with different cements, and separated in a similar manner after 13 months, had a shade of uncertainty thrown over them by the absence of clear distinguishing marks on the different pairs1 to show the nature of the cement and the quantities of sand mixed wilh it. A necessity arose for their removal from the place where they were first deposited, and the sergeant who superintended their movement had quitted the Establishment before the experiments were complete, and the difficulty of distinguishing the quantities of sand io the specimens had been ascertained. The results are not, therefore, given in full, but though in individual cases there was a little difficulty in deciding what cement was under trial from appearance alone, yet there was ample proof that at the end of the 13 months Scott's cement with 1, 2, and 3 parts of sand had quite doubled the 1trength which it had gained after one month, and had preserved its relative position ; and that \Vith 3 parts of sand, the mortar joint was stronger than an average stock brick.

A second series of experiments was made on rectangular prismoidal blocks composed of cement and sand in different proportions. The blocks were 4 in. long and 2 in. square in section, and were broken by a stirrup over the block, acting transversely by means of weights attached below. The supporting stirrups were placed at a constant interval apart of 3 inches. A full description of this method of testing the strength of mortnrs is given in the works of General 1'rcu~snrt and Sir Chnrlcs Pasley.

ON TUE MAN U1"A<.:1'URl: 01~ A NEW CBMJ::NT. 147

TABLE Ill.

Deduced from the results on which Table I. was compiled, and giving the relative uncertainties of the cements with varying p1·oportions of sand. The numbers are obtained by dividing the difference between the lowest result and the mean result in each case, by the mean result. The highest decimal therefore indicates the most uncertain mortar:-

COMPOSITION OP MORT.A.R,

N .uu: or C•Mll1'!T. 0 land. I sand. 2 &and. S sand. 4 und. 5 li.nd. 6 sand, l cemt. l cemt. 2 cemt. 3 cemt. 4 cemt. 5 cemt. l cemt.

RBxAR.li:8.

, _____ -------------- _______ , White's Port~ ( ... ·4 {

Without sand, the ·5 ·5 ·5 ·8 ·6 bricks generally land . . .

broke .

Medina, •. , ·6 ·4 ·2 ·5 ·6 l· ·7 { ,Vith 5 and 6 sand only 4 trials made.

···{ With 6 sand, the

Roman •••• ·I ·3 ·3 ·5 ·7 I· joints would not bear handling.

Atkinson's. ... ·I •4 •O ·3 ... . .. Bath ... ... ·l ·2 •2 ... . .. . ..

···{ With 6 sand, the

Lias lime •• ·4 ·5 ·2 I· l• l · joint! broke in

Scott's cement, l handling the bricks

B quality .• ·6 ·2 ·4 ·l ·2 •2 ·3

It is worthy of remark that this table indicates that the quantities of sand generalJy specified for mortar of different cements are such as give nearly the least uncer .. tainty in their use.

TABLE IV.

The numbers expre" the weight in lbs. which fractured the blocks by weighting them at the centre after they had been made for 1 month :-

COM1'081Tl0lf 01' MORTAR.

N.a.JIB 01' CEIU:lfT. l aand. 2sand. 3 &and. 4sand. 5 11and. RE!AU.11..KS, lcemt. lcemt. 1 cemt. lcemt. lcemt.

,vhite's Port- }m 538 322 158 151 land ....

···{ \Vould not bear the weight of

Lias lime .•. scale ( 25 lbs.), exceptiug with-... . .. ... ... out sand, when the block bore 126 lbs.

Scott's B qua-} 382 333 263 242 172 lity .• , ••

N.B.-Thc numbe,s are the means of 5 trials.

O\ TJrn ::\IA!'il' F.\ C'fURl:: OF .\ NEW ('EMENT.

TABLE V.

'l'hc numbers express the weight in lbs. which fractured the blocks after 13 months:-

Co;vP0StTI0lf o, Mo11TAll.,

Nu1sorCllllE:!l'T!, 1 sand. 0 oaod . 13 nml. Ruu.r.xs. I oemt. l cemt. l cemt.

Roman . . . . 562 214 102

Lias lime .•• 158 .. · { With 2 and 3 parts sand, the blocks broke ... with the weight of the scale (25 lbs) Scott's cement, } 780 650 410 D quality .

TABLE VI.

Showing the quantities of sancl generally specified in the case of each of the cements for dry brick-work; their relative resistances to fracture with these quantities; the rdative uncertainty of satisfactory joints under such circumstances; aud the approximate cost in London of a cubic yard of each description of mortar :-

'E~ :s

Uh ]~

NAllE0FCE:UB!iT, U1 lH ~s REltAR.li:S, 'oci i] ~ ~ 0 u~ u;= "~

White's Port- } s. d. ( For comparative resistance, a mean

land .. 3 1 ·5 17 3 l :~;~\:i·tfi' ;ntet;:~~!;~i~~~:;~i!~

}.Iedina. 2 ·72 ·2 { Not much used for mortar in ... London .

Roman ..•. I ·72 ·3 17 0 {For comparative uncertainty a mean

Atkinson's . 2 ·46 ·2 ofresults with 1, 2, and 3 sand taken. See Table V. This cement is prin-cipally used for casting.

Bath. ..... 2 ·35 ·2 . .. Little used in London.

Lias lime. 2 •,32 ... 10 0

Scott's cement, l 3 ·85 ·I 10 G { Four parts sand to one of cement B quality •. are used by Capt. Fowke.

In point of labour in laying the bricks, the cements would stand much on an equality with the proportions of sand gi,·cn in the table, the Roman having the advantage when the amount of fair face work is considerable in proportion to the whole; but to counterbalance this advantage there is the necessity of mixing small quantities only at once, and the loss occasioned by the cement frequently taking a set before it can be used, 'l'hc Lias lime is more troublesome to make

OX TUE MANUFAC'l'URE Or' A NEW CEMEX'!'. 14U

into mortar, because it must first be slaked, and when slaked, it requires much labour in properly mixing. The bricks can, however, be more easily laid in it, and the joints be more quickly struck or made fair with the trowel in fair face work. It is considered also less necessary to wet the bricks, but it is doubtful wh£ther Lias lime does not suffer quite as much from being applied to dry absorbent surfaces, as the cements do.

It will be seen t4at so far as careful experiments on a small scale will afford a criterion for judgment, the Scott's cement of B quality, though inferior to \Yhite's Portland in point of strength, offers many advantages for ordinary brick-work.

It must be borne in mind, also, that the Portland cement tried in comparison with it, though not the strongest made (that prepared for the Dover harbour works by Messrs. Lee, see Table I., being stronger) is nevertheless of such 11cculiar excellence and regularity of action as to enable the Messrs, White to obtain a higher price than other manufacturers. The Portland cement in the market is of very variable quality, depending much on the temperature at which it is burned. Properly burned Portland cement leaves the kiln in a state of flinty hardness, and the expense of grinding it to a powder forms an important item in the cost of production. The n1nnufacturer endeavours to reduce the wear 011 his machi11ery as fat· as he can without risking the condemnation of the cement, and he does so by insufficient burning, whereby he not only obtains a softer material to grind, but saves fue1, and sells for the bushel a smaller quantity of cement. The French, from their knowledge of this, in their pur­chases of English Portland cement, reject all that does not come up to a certain standard of specific gravity, and many now regard weight as a test of quality of other descriptions of cement also, but in this they err.

In the preparation of Scott's cement there is no such opportunity of chrapening production at the expense of strength.

TABLE VII. Showing the weight required to fracture concrete prismoidal blocks 2 in. square

in section, and 3 in. between the points of support, when weighted in the centre in the same manner as before; the blocks were allowed to dry in the air for 17 days, and then were immersed in water for 12j months before bcin g broken : -

N .UtE OJ' CBMElfT. Qua.ntity of Resistance No. of experl- REM"ARli:8, shingle used. to fncture. mentsma.de.

--------

{ Blocks of the same description averaged over 1,132 lbs. with-

Portland. ... 4 862 6 out fracture, when allowed to remain in the air for the whole of the above period,

Medina •. . . 4 335 3

Lias ••••.. 5 134 20

Scott's cement, ) { Blocks of the same description 5 409 21 left in the air for 13 months

B quality , . fractured with 942 lb.

I I,

150 0:-1 'l'IIE 1l.\.NU.!-'.-\.Cl'U1U:: OF A XEW CKMEX'1',

From these experiments it would Beem that though the Scott'~ cement (B quality) loses more than hnlf of its stl'ength from its immersion, )·et that it retained sufficient to show that it is much superior to Lins lime for water works, when it can set and take nn outside skin in the atmosphere before the water covers it. In coffer-dams these conditions would to a certain extent be secured, but not fully so, for in heavy masonry, such as is required when coffcr-dnms are necessary, the joints would not harden so quickly as in small blocks, and would not dry before the water was admitted.

For the backing of a wharf wall it is believed that it would also be superior to Lias; but for immediate immersion, experiments indicate that it yields more on the surfa<'e than Lias when both are mixed with sand, though it consolidates better internally.

The re:mlts hitherto given, and the opinions expressed, have been confu·mcd by experiments carried on in the Chatham Dockyard by order of Col. Greene, Director of Engineering and Architectural Works to the Admiralty; and at Paddington, by Mr. Linn for Mr. John Fowler, C.E.

It will be perceived from Table VII. (see column of remarks) that Scott's cement, of B quality, has great strength in dry concrete. Captain Fowke has taken advantage of this in the construction of fire-proof floors, for the Ken­sington Picture Galleries. It is also well adapted for stucco, as will be seen from the following table of comparative results obtained by Captain Schaw.

TABLE VIII.

Showing the relative advantages after 4 years, in point of colour and of hardness, of different cements applied as stucco to a brick wall, the highest numbers expressing the best results in the case of hardness only:-

CoLOua. CoMPAlU.TIV. H.UtDNBSS.

COUPOSITION OF MOIi.TAil. NAXB OJ CE:UBl'IT. ---

Order of 1 sand. 2 sand. 3 Hnd, I • .. nd. 5 61llld. merit. lcement.. lcement. 1 cement. 1 cement, lcement.

---White's Portland .• 3 100 85 80 75 70

Medina ••••••• 4 90 70 45 40 30

Roman. : ••• , • , 6 65 45 25 IS 10

Lias lime. ..... 2 45 40 35 20 15 Scott's cement, B

quality •••••• } 1 100 75 70 65 50

The Scott's cement was of a more uniform tint throughout, as well as of a better colour, than the other cements. It had also, up to three parts sand a harder surface, resisting scratching with a sharp tool better even than the p 't­land cement, though breaking sooner under the blow of a hammer. Both h=d­neH of surface and tous:hn••~ were carefully considered by Captain Schaw in ass,grung the numbers given m the table.

ON THE MANUFACTURE OF A NEW CEMENT. 151

The 8cott'!-l cement of D quality appears then from careful experiment to give great strength in dry brick-work; to make concrete of great excellence for dry situation, i and to make a very good stucco, of better colour and more uniform tint than any of the other cements in use, and to be, also, of cheaper applien~ion. For hydraulic p~rposes, n~twit~standing the results shown by Table VII, the cement of quality A, which will next be treated of, is recom­mended in preference. In practice the cement of B quality has been em­ployed with success on government works at Hythe and Dover; for an escarp wall at Tilbury Fort, by Capt. now Lieut. Col. Ord, R.E. ; in the construction of magazines and sicle-arm sheds at Sheerness, by Lieut. Col. Montngu, R.E. ; and as a stucro, by Capt. Inglis R.E., and others, a.t ,voohvich. It has also been used very extc-nsiYcly nt the Kensington Museum for brick-work and plastering, by Capt, Fowke, R.E., to whom the inventor is much indebted for valuable advice and information on many points connected with the manipulation both of the cement and plaster. The value, indeed, of the assistance which Capt. Fowke has given, especially in the early days of the invention, could be appreciated only by one who has endeavoured to introduce a new material, and knows by experience how difficult it is to fight against the prejudice of workmen, and how few will p11t themselves to the trouble of doing it.

The writer has also to thank Major Gallwey and Lieut. Col. Collinson, R.E., and he remembers with great pleasm·c the first trial made by the latter officer, in a shell room in the Arsenal, when the cement was made, a bushel at a time, and beaten to a powder for sifting, with wooden rammers. Lieut. Col. Collinson, also, as soon as the manufacture was established, employed the cement in works at Aldershot. The inventor's obligations to Captain Schaw will be evident from the part he took in the experiments which have been above tabulated.

The cement of A quality is very much superior for_ hydraulic purposes to that which has been described. No comparative experiments on its strength to resist fracture, similar to those tried with B quality, have been made, but Mr. Mac­donnell, C.E., Superintending Admiralty Engineer in Chatham Dockyard, has reported to the Director of Admiralty Engineering Works, as the result of an experiment made by him, its great .. superiority to Lias lime for hydraulic purposes.

The experiment consisted in placing two wooden boxes 3' X 3' X 2' deep, filled with concrete of the materials under trial on the river shore, in a position where they were covered by t)le water for 18 out of the 24 how·s of the day. The concretes consisted of 6 parts of ballast to 1 of Lias lime, and 6 parts of ballast to 1 part of Scott's cement A quality, and the wooden boxes were removed at the end of one month. By this time the Scott's cement had greatly the advantage in consolidation, and in a few tides afterwards the whole of the Lias block was swept away, whilst the other resisted even the severe winter frost, and still continuing to harden, is now almost like stone.

This cement would be better adapted than th(first described for pointing, as well as for hydraulic purposes, and also in all situations when the work would remain in a damp condition though not actually in water. It is, however, equally suited for dry brick-work and for stucco, and it resists for a longer time the injurious effects of exposure before use to a damp atmosphere.

]J2 ON TIIE MANUFACTURE OF A NEW CEMRXT,

It has nlready bC'en stated that the cement nvnilable at Porbmouth, Brighton, and the South-East Const hns hydraulic properties intermediate between these two qualities. The factory for it has only lately been cstaUlishccl, but it bas nh·cndy been tried by }.fojor Gallwey, R.E., who has reported Yery fav01uably of it.

Six pairs of bricks were cemented together with it, at Chatham, in the m[lllner ah·eadv described. The mortar was composed of 2 parts sand to 1 part of cement. T0hey were separated at the encl of three months. In one 1rnir the bricks gave way fu·st; in the case of the remaining 5, the nvcmge breaking weight of the joint was 436 lbs. The sample was from the first trial of the process made by l\Iessrs. Rickman, and was not finely grow1Cl. The sand also was inferior to that which was used in the earlier experiments.

The cement from Lias lime was first used b)· .Major Gallwey at Portsmouth, when the Contractor, Mr. Piper, had erected a small oYen with the writer's permission, and em played the J)Tocess for his own satisfaction.

In a trial made with it, in comparison with Portland cement and Lias lime, for concrete to be immersed at once in vrnter, and in comparison with l\Iedina cement for stucco, the follo,ving results were obtained. The numbor:::1 given are the means of the independent judgment ( which almost coincided) of three officer~, and express their opinion of the relative merits of the materials under trial. 'l'he numbers actually assigned by these officers have been raised proportionally, to keep to the system followed in Table YIII.

TABLE IX.

Showing results obtained at Gosport with Scott's cement in comparison with

other cements, for concrete and for external stucco-work on brick, after three months :-

Co?l'CRBTE. STUCCO.

6 ballast. 10 ballas~. 1 sand. 2 S!lnd . 3 eancl. NAME OP CEllBNT, .RBMABJ,a.

1 cemtn~. l cement. l cement. 1 cement. I cement.

CoMPOSJTJOX OP I Co:uPos 1T10N OP I ------<--- ------ ------ -------

l00 . • • • . • • .• f I Only tried in con-Portland .•••

Medina No, 1 .

Ditto No. 2.

Lias lime •.. Scott's cement

prepared from Lias lime ••.

13·3

} 50

l crete.

, . . . , , 69·3 . • . for these experi. { S:unple obtained

5!·8

5·16 100 77

ments.

{I J~l~s st;;c~h~n io~~ • • • of the same date

nearly • . • , { Only tned iu con-

61-6 I crele.

ON TIIE ;\[ANUFACTl'RE OF A NEW CEMENT, 153

Ou com1mring these numbers with the numbers assigned by Captain Schaw to Medina and Scott's cement of B qualitr (Table VIII) it will be seen that the Scott's cement made of Lias keeps its position as a stucco, whilst, for concrete to be immcrt::ie<l at oner, it shows itself four times as strong as Lias lime after three mouths' immersion, and that, with a far larger proportion of ballast. '!'his cement has nbo been experimented on in Chatham Dockyarcl with successful results. It retains its cementitious properties when exposed to damp before use, better than either of the preceding clescri11tions of Scott's cement, and in this respect is superior to Roman and Medina cement. Incleed, generally, the Scott's cement, whateYcr lime may be its basis, has the adYantage over the other kind.<:o of cement alluded to in this paper, of not entirely losing its binding properties by exposure in the state of powder or with long keeping; exceptiug after very lengthened ex1Josure, it still acts better than the lime from which it was prepared, whereas the other cements, when exposed to the air, are soon no better than mud. On the other hand, when applied to very dry absorbent surfaces the fuilm·e of the cement of B quality is more entire: not only is there no adhesion, but the cement actually crumbles abroad and expands like slaked lime. It behaves, however, in this way, within 2-1 hours of its application. And it fairly admits of question whether such a peculiarity is a disadvantage. "'ith all cements, it is specified that the surfaces it is laid on shall be "·ell wetted, and no good work can be done if this is neglected, but, whereas generally constant watching alone will induce the workmen to comply with their orders in this respect, here they have no option, as neglect is immediately followed by detection.

In proportion as the quantity of argillaceons constituents, naturally present in the Scott's cemeut, increases, this peculiarity is less marked, and when prc­pm·ed from chalk lime, containing oYer 30 per cent of such constituents, the cement suffers less from dry su1·faces than any of the other cements experimented with. All cements suffer more, as might be expected, in proportion as the quantity of sand mixed with them is less.

Neither of the cements macle by Scott's process are quick setting cements, ancl the most hydraulic are the slowest. They are not therefore so well adapted for tide work, or tmderpiuning, as Roman au<l ~Ieclina, but for general building purposes, quick setting is a clisadYantage. Bl'icks are continually displaced by the feet of the workmen or by planking, after the quick setting cements ham lost the property of healing a fracture in the joint. Not only is this source of weakness remedied when the setting is slow, but the joint generally sets under pressure which gi,es it increased strength. Ra11idity of set in samples of the same clescription of cement is a. test of thell· freshness, ancl, therefore, to some extent, of thell' condition, but it affords no criterion of the quality of specimens of cements of different kinds, nor of the ultimate hardness they will attain.

ON TIIE PROPERTIES AND APPLICATIONS OF Scorr's PL.\Sl'ER.

The following remarks apply to the plaster as macle by :Messrs. Lee, Son, and Smith, of Halling, and Messrs. Rickman ancl Co., of Lewes. The former supply London, Chatham, Sheerness, Do,·er, and Shorncliffe. The latter firm i;;upplir~ IJnc;tings, Bright(ln, T>orhnnou1h, Go,.,;port, aml Southam11ton.

V

ON THE MANUFACTURE OF A NEW CEMENT,

It is principally used for internal plastering, but may be employed for cxter1lal work executed in summer time on ·,ralls in unexposed situations, and when the damp of the ground cannot rise to, and saturate it.

The cost of the lllaster at the above mentioned })laces is not one-fifth part of that of Parian and the other gnlseous cements, and though it does not trowel to so transparent and marble-like surface as the more expensiye qualities or them, yet it gets a harder glaze on its surface and would only be benefited by repented washings, whereas they would lose their polish by such treatment. Scott's plaster, when hardened, consists mainly of carbonate and silicate of lime.·, both of which are insoluble. The Parian cement, and ~fa.rtin's and Keene':-, cements, on the other hand, mainly consist of sulphate of lime and other more ~oluble substances. Hence for the wm·ds of hospitals, where a ha1·d1 impen·ious, non-absorbent surface "-hi.eh will bear washing is a desideratum, the plaster. independently of its lower price, is much to be preferred.

It is a very difficult matter to ascertain precisely the fair cost of labour and material in plastering. l\Iodes of executing the work differ very much, and no two men will use a similar quantity of sand. Some plasterers, when they have a loamy sand, will add much more of it in their "stuff" than when the sand is sha1·p and clean, and there is no exact standard for the degrees of finish to be given to the setting coat. The quantity of hair, also, specified in different cases, varies widely. From a careful experiment made by Sapper labour, in the offices of' the new Mess Establishment at Brampton Barracks, under the superin­tendence of Captain Schaw, and from the testimony of those who have used it for some time, it would appear, on a comparison of Scott's plaster with lime and hair, that-

1. There is a considerable saving of labour with the Scott's plaster in making the mortar or " stuff."

2. In rendering on brick the labour in the two c:.uses i,; about the same. 3. In floating on brick there is a considerable saving with the plaster in point

of labour, because the Derby, or long float, does not frequently drng the "stuff" from the surface as is the case with lime and hair "stuff," nor does it leave cracks to be made good with the hand float.

4. "'b.en the setting cont is trowelled smooth for painting, more labour is necessary with Scott's plaster to put a polish on it; but when left us rough :stucco from the hand float, the ad,-antage lies with the Scott's IJlastcr.

5. On lath-work, especia.lly on ceilings, the use of Scott's plaster does not offer the same degree of advantage for three reasons:-

Less saud is used i hair must be mixecl with the mortar; autl. from the absence of suction the coats cannot follow one after the other as quickly as on brick. On the other hand, when great strength is required, as for barrack ceilings, the lime and hair fails much more quickly.

6. The inconvenience of waiting for the differe11t coats to dry is entirely obviated o~ brick-work, ancl almost so on lath-wol'k, when the plastering is txecuted with Scott's plaster.

7. Two coats only, a floating nnt.l a setting coat, al'e l'equ.ircd fo1· the finest work with it.

8. In large and lofty huildings of many stories, there is n great Paviug of labour with it in the rC'nHn-al and c-recting of seaffoldiug·, s:i11f'c the whok uf 1.\

flat can be finish~d at oiwc :i.ncl without :my tlPlay.

ON TIIE MANUFACTURE OF A NEW CEMENT. ],)5

9. The work is not defaced by every accidental blow receiYed during the completion of the building, Rb is the case with lime and hair plastering; nor is it necessary to make repairs after the carpenters have com1>letcd thell' linings, &c.

10. In point of hai·dness and durability there is no comparison between these two materials, the superiority of the Scott's plaster is so great.

ll. A building can be occupied, painted, and papered much more quickly when the Scott's plaster has been used than when :finished in the common method.

It is believed that, on the whole, its use is attended with no extra expense in the :finst cost, when the distance of carriage fo1· the plaster docs not exceed 30 or 40 miles, and with an ultimate saving from its g1·eater dw·ability and the speedier occupation of the building. On the question of the labour required to opply it, however, there are great discrepancies of opinion, and not in favour of the cheapness of the Scott's plastel', nl'ising in great measure, perhaps, from the (•xperiments tried in such instances having been on a small scale, the 11lasterers l>eing quite unused to the materials, and both they and their immediate em11loyers inte1·ested in representing the labour required on it to be great. Many of the experiments, too, ha,e been made by day-work, and the results compared with work done by the piece, which method of ascertaining comparative prices of labour is hardly to be relied on,

EXAMINATION OF THE CEMENT,

"\\'lien genuine and in good condition, the cement consists of a fine homoge­neous powder of a tint similar to that of the unslaked lime from which it is prepared, and when injured by the all' it gradually assumes a lighter tint approaching that of the slaked lime, and at the same time becomes more impal­pable. "\Vhen thus undergoing air spoiling, it approximates also in its action to that of the slaked lime, though for a yery long time it will gh-e a stronger mortar than the unprepared lime will.

Samples for trial should neYer be taken from quite the top of a cask of cement, nor should a cask be rejected because a small 11ortion i:tt the top or nt an open i:,tave has whitened, for this must frequently occw· in the fair way of trade, and such injury will not sensibly affect the bulk when made into mortar.

Small sample bottles hermetically sealed would assist both to determine whether a supply was manufactw·cd from the lime guaranteed, and in what condition it is as 1·egards its age by a comparison of colow·, siuce the process produces no alteration in this respect.

When air spoiled, the cements have taken up a considerable amount of moisture, and if a small portion of such spoiled cement (about 20 grains) be heated to rccb1css in a glass tube in the flame of a spllit lamp, the water is driYen off and condenses in the upper part of the tube, thus affording, by the quantity of ,,,atcr which collects there, some criteiion of the exposw·e which the cement has under­gone. It must be remembered, however, that excepting from. a?solutcly frei:,h <.:cmcnt, some indications of n10ist.ure will always appear when it 1s so heated.

Li6 ON THE MANl'FACTl'RE OF A NEW CEllENT.

"'hen a portion of the cement of B quality is made into a stiff paste with water, mid this paste is moulclccl so as to form a cake about 6 inches in diameter and { an inch thick, it should set within 6 houxs. Cement of A quality, and that prepared from Lewes lime, may take a little more time to sot, and the cement prepared from Lias will require still longer. If the Lias cement takes even 24 hours to set it may do well, and its fhst set is not one of great hardness; a mru:ked change, howe,er, should take place nbout the scYenth or eighth day. As has been already said, slow setting, when it docs not arise from air spoiling, is not generally prejudicial in building.

Should the cake so made heat up and show signs of slaking to powder, the cement bas not been sufficiently prepared. If these signs arc rcstrictecl to the centre of the cake, a day's exposure to the atmosphere would remedy the defect, but this might be inco1wenient to arrange, and it is safer to irn;ist that the cement with this trial should not generate more than a trifling elevation of tem1Jcratnre.

If a portion of the cement is made up with water into a stiff paste, which is then moulded into the bottom of a tumbler or other vessel and covered with water, it should gradually stiffen and finally set; if, however, instcacl of acting thus, it becomes more bulky and swells up, the cement should be rejected. It is then little, if at all, removed from the condition of common lime, and might be used for it without disadvantage. 'The process may be ineffectual in con~ verting the lime into cement, but it cannot spoil it.

The plaster, which is likewise to be in a state of fine powder, may be tested by ascertaining whether it has imbibed much moisture, and by the manner in which it sets in the air, as is recommended for the cement. If a cake of the size above specified does not become so hard in 12 hours as to be fairly termed set, the plaster is not what it ought to be. In 24 hours it should harden on the surface as firmly as plaster of Paris would do in the same time, and in two or three days the exposed portion of it should resist scratching with the finger nail.

If the Chemist to the ,var Department is referred to as to the goodness of ::i.

t:.upply of cement or plaster, the sample sent him ought not to be taken from quite the outside of the bag or cask for reasons already assigned, and it should be forwarded to him in a well corked or stoppered bottle, with a label on it to inform him which of these materials it is intended for, and what description of lime has been guaranteed for its production.

lNSTilUCTIONS FOR USING TUE CEMENT.

The cement should be kept from the action of the air. Casks afford the best protection, but bags are cheaper and ma.y be substituted for them whenever the consumption is rapid. As has been already stated, the cements prepared from the more argillaceous limes resist the action of the air best.

Cement ofB quality may be employeG. as mortar for dry brick-work and masonry with as mnch as 4 parts of sand to 1 of cemcn t, if the sand is sharp and good, and

OX TUE M.\NUFACTUHE Ql-' A NEW CEMEN'l', 157

with 3 parts if it is loamy. For stucco nlso, these proportions should be used in the floati11g i and for the set, equal parts of sand and cement if the surface is to be trowelled smooth, or 3 parts of sand to 1 of cement for rough stucco. As much as 6 parts of sand have been used in mortar for brick.work, aud 5 parts for plr.stering1 but such quantities arc excessive. Three parts are recommended.

In concrete work 8 or 10 parts of ballast are to be used for dry work, and 6 parts in foundations.

'l'hc surfaces, particularly in plastering, to which this cement is applied, must be well wetted; if laid on dry absorbent walls as a stucco, it may crumble and fail in 24- hours. In massive walls there will be fair adhesion, where no layer of dust intervenes, if the bricks are wetted in the stack. In a thin wall every brick should be dipped before it is laid; and whatever mortar may be used this plan alone is to be relied on.

The workmen must be cautioned not to mix too much mortar at one time. It ought neither to commence hardening nor even grow warm on the mixing board. Directly any tendency to warming makes itself perceptible, the quantity made up at one mixing should be reduced, so as to have less delay before it is put into the work. It has already been stated that this is not the quality of cement recommended for either damp situations or hydraulic work, but if so used, the quantity of sand in damp walls should not exceed 2 parts to 1 of cement, and for hydraulic purposes equal parts of cements and sand.

CEMENl' OF A QUALITY, LEWES CEMENT, AND CEMENT PREPARED FROM

LIAS LIME.

Generally these cements resist absorbent surface.s better, but nevertheless, thorough wetting of the materials with which they are used is not to be dis­pensed with ; 4 parts of sand to 1 of cement ought not to be exceeded on dry walls, whether for brick-work or stucco, and 3 parts are recommended. For damp walls 2 parts of sand to 1 of cement are sufficient, and in cases when immersion in water is to be immediate equal parts of cement and sand should be used.

In concrete, the cement prepared from lias lime and that of A quality will bear 1 O parts of ballast, whether in air or immersed ; the Lewes cement makes excellent concrete with 8 parts, but probably they would all answer better in water with 6 parts-the proportion usually employed with other cements nncl }imes. They are well adapted both for dry sites and for hydraulic works.

It is to be understood that in all cases, as far as strength is concerned, it woultl be better to specify 1 part of sand in preference to 2, 3, or 4, but with so bll1a11 it

proportion of sand, a thorough wetting of the brick, or other surface it is laid on , is absolutely cs:;c11tial to secure the proper action of the cement.

108 ON THE MANUFACTUTIE OF A NEW CEMENT.

INSTRUCTIONS FOR USING THE PLASTER.

Like the cement, it must be preserved from the air; and here also the magni­tude of the work and the consequent ra11idity of consumption must determine whether it shall be allowed to be sent in sacks or not.

The rendering coat on brick may be executed with 2 or 3 parts sand (4 parts are sometimes used but are not recommended) and on lath 3 parts cannot be exceeded without loss in point of labour. On brick, no hair is needed; on lath, the quantity employed with lime and hair is to be used.

For the setting coats it is useless to lay down a precise rule, as esrery plasterer will manage to follow his own idea notwithstanding. Perfect surfaces, how­ever, may be trowelled off with any proportion, between 3 parts plaster to 1 part of sand and equal quantities of plaster and sand.

On brick, the finishing coat is to follow on after the floating coat as soon as possible; and the floating coat after the rendering coat, if the latter should be judged indispensable in any peculiar case. On lath, it is better to allow the floating to consolidate before the II set" is laid on, as otherwise, strong lntbs will by their warping crack both the floating and setting coats.

No more mortar should lie made at one mixing for a rendering or floating coat than can be used in one hour, though this time is often much exceeded without apparent injury. In setting, the mortar should not be left more than twenty minutes on the mixing board.

Old walls must be well wetted before applying the first coat. With green walls the work will be surer if this is done. On lath, when the floating is allowed to dry before the setting is commenced, '\Tetting is of course indis~ pensable.

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159

PAPER XVII.

ltEPORT ON THE SIEGE OPERATIONS CARRIED ON AT JULIERS IN 8EPTEM8£R

18,G0, FOR THE INSTRUCTION OF THE PRUSSIAN ARMY, ESPECIALLY WITH

REFERENCE TO THE EFFECTS OF RIFLED GUNS;

BY LIEGTENANT COLONEL ROSS, ROYAL ENGINEERS,

ACCOMPANIED BY EXTRACTS FR0ll A REPORT ON THE SAME SUBJECT Df

CAPT. GIESE, PRUSSIAN ROYAL ENGINEERS,

TRANSLATED BY l\1AJOR GENERAL HAMILTON, C.B.

Juliers is situated nt the point where the road from Aix-la-Chapelle branches off to Dusseldorf and Cologne, and, before the railroads between these plp.ces were constructed, it was considered n position of some iruportance ; but since the completion of these new lines of communication the same strategical value no longer attaches to it.

The town stands on the east or right bank of the river Roer, the communica• tion over which is by a wooden bridge on square stone piers, covered by a strong hornwork as a tete-de-pont.

This hornwork is elaborately finished, ha·cing a loop-holed gallery all round the scarp, with two tiers of very well built casemates in the left demi-bastion ; in the upper tier there are embrasures commanding the road from AL'X.-1n­<Jhnpelle, the lower tier having loop-holes which see into the ditch in front.

'l'he works surrounding the town consist of four bastions connected by very long curtains, ,vith wet ditches, and four ravelins, besides some other detached works. The scarp walls of all these bastions, and parts of some of the curtains, have been destroyed by mines, in furtherance of the views of the Prussian government with respect to the fortress.

The citadel, which is on the north side of the town, is square, and consists of fow· regular bastioned fronts with wet ditches, and an interior line forming a kind of cavalier. The scarps are on an average 42 feet high and 12 feet thick at the foot, with counterforts of the same depth. They are built of brick en decharge, with a gallery all round, and are in excellent condition; there nre also three n:1.vclins, which, ns well ni the bastions, are covered by countergua.rds; and between ravelin No. 2 and the counterguards 2 and 3, on each side of it, there is a detached wall covering the faces of Bastions 2 and 3. This wall is said to have been built by the French during their occupation of the place.

There nre likewise, on the north side of the citadel, three advanced lunettcs, also built by the French, When the Prussiaru regained possession of it, between

1130 REPORT ON 'l'HE SIEGE OBERA'rIONS IJ.\RRTEn ON AT J1JLIERS.

JO nncl .50 yenrs ngo, they constn1cted tbo detached wnll and gorge oflunctte 11, ns well as the different block-houses in this nnd in the other luncttes and outworks. (See Plan).

'l'he position of J uliers is clefecth·e, inasmuch as it is completely commanded by the Merschen heights, situated at about 1,000 or l ,200 yards on the north side of the citadel ; the Emperor Napoleon I. recognized this weakness, and during the time that the place was held by his army he caused them to be occupied by advanced works, the remains of which still exist.

For this reason the Prussian government decided upon levelling the fortificn~ tions around the town by mines. These demolitions were commenced in July last, but the siege operations against the north side of the citadel were com­menced subsequently, and were undertaken for the purpose of affording the officers and men of the Prussian army an opportunity of seeing works of this description on an extensive scale.

The whole of the glacis round the town and citadel has been planted with trees up to the crest of the coYered way, which were cut down on the front of the citadel against which the works of attack were directed, affording mateda.ls for making gabions, fascines, &c. The roots of these trees offered a great impedi­ment to the Sappers in carrying on the siege operations.

It may be added that the fortifications of Juliers are said to date from a very early period, the greater pa.rt of the works having been built under the direction of a Spanish Engineer between the years 15:M aml 1550.

EXPERIMENTS IN BREACHING BLOCK-HOUSES,

On the morning of the 17th September, at 7 o'clock, the operations commenced by firing at two block-houses, one marked E, in lunette C, the other marked D in the ditch in front of this lunette, at a distance of 1,250 Prussian paces, with six guns; viz., two brass guns and four iron guns, all rifled, breech-loading, and of 12-pdr. calibre, carrying a conical shell•, exploded by means of a con ­cussion fuze. The weight of the shell was 27 lbs.,t of the charge 1-rbth lbs., of the iron guns 2,700 lbs., and of the brass guns 1,300; the elevation was 6°160 ths, and the full charge was 2,-\,th lbs.

• The weights given in this report are all in Prussian pounds, 100 of which are equal to 103 English pounds nearly; and the dimensions of the walls are given in Prussian feet, 100 of which are equal to 103 English feet nearly.-Eo.

1" The weights of the shells used during these operations are thus stated in the Report made by Captain Giese of the Prussian Engineers: -

6-pdr. 12-pdr, 24-pdr.

lbs. loth. lbs. lath. lbs. loth. ,v eight of iron of the projectile. 7 15 17 16 36 22

Do. of leaden envelope • • 5 14 10 14 17 2 Do. of metal fuze, &c. . • 4 5 5 Do. of bursting charge 15 28 2 0

Total weight of shell charged. 13 18 29 3 55 29

The pound is equal to 30 lot h. ED.

REPORT ON TITE SIEGE OPERATIONS CARRIED ON AT JULIERS. 161

The brass guns were originally of the old smooth-bored pattern, but bad been converted into breech-loaders and had been rifled. The iron guns were new.

The block-house D measured about 25' X 25; exterior dimensions; the walls were of brick, 2~ ft. thick, and were built with indifferent mortar; it was covered with splinter proof-timbers, with about two feet of earth above. It was so situated as to be quite concealed from the two brass guns which were directed against it, as explained by the accompanying section (Fig. 1).

The block-house E in lunette C was 6-!' x 34' exterior dimensions, and the walls were of brick, 4 feet thick; the mortar was of the same quality as in the other, and it was covered with splinter-proof timbers and earth like the other one. Inside of each block-house were strong wooden posts to support the roof. The annexed section (Fig. 2) will explain the position of this block-house with regard to the parapet which intervened between it and the four iron guns directed against it.

32 rounds were fired from the two brass 12-pdrs. under the above conditions at block-house D, of which 15 rounds appeared, from where the spectators were situated, to take effect upon it.

On inspection it was found that a breach about 4 feet wide had been made at the south-east angle; the splinter-proof timbers were Yery little damaged, but the building was rendered untenable, although the effect of so many shells was not so great as might have been expected; as however the block-house itself was entirely concealed from the spectators whilst the firing Wt\s going on, it is impossible to speak confidently as to the number of times that it was actually struck.

64 rounds were fired from the four iron 12-pdrs. at block-house E, of which 37 took effect, making o. breach in the side next the battery 81 X 61 6"; the splinter-proof covering was but little injured, and not much of the earth above it was blown a war i only one shell had gone through the building and taken effect against the opposite wall: most probably it had gone through the opening. The penetration of single shots into the brick-work was about 911•

The object of these experiments was to ascel'tain what effect could be produced by artillery firing with reduced charges and at high elevations, from a distance, at buildings concealed from the guns directed against them by intervening works, and situated at no great distance within those works; the results in both these instances were successful, as any troops occupying either of these buildings would have been driven out of them.

EXPERIMENTS IN BREACHING DETACHED SCARP "' ALLS.

The next experiments were commenced by firing with the same six guns at 800 Prussian paces, against the detached wall in front of the right fin~ of lunette B, the wall being concealed from the guns, as explained by the section (Fig. 3). During this series of experiments the guns were fired with the fuU charge, viz., 2r'vth lbs., and with the same shell as before.

'l'he part of the wall to be breached was marked out into squares of about 2 feet each side, by horizontal and vertical white lines; the wall was built en decbarge, and of brick, the arches extending through to the front of the wall. During the first round from each gun no shell hit the '"'all, they all fell 0hort,

X

162 REPORT ON THE SIEGE OPERATIO:<S CARRIED ON' AT JULIERS.

and burst upon striking the ground; of the next round four shells struck the wall and burst in it, producing a good effect, the penetration averaging from 12 to 15 inches.

After 5 rounds more from each of the six guns the corner stones nt the left angle of the wall towards the bottom were much injured, part of the brick-work below the arch on the left was pierced, the embrasure in that arch carried away, nnd the bottom of the wall between the 2nd and 3rd arch severely shattered.

5 rounds more from each gun increased very considerably the opening that had been already made, and pierced besides the wall to the left of the embrasure in the cent.re arch: the top of the ,vall between the 1st and 2nd arches was also knocked away.

5 rounds more from each gun, or 102 rounds in all, enlarged very much the apertures made under the first and second arches, but the pier between them was still standing, although cut vertically in two.

The last 5 rounds, or 132 shots altogether, brought down the wall en masse, making a breach 32 feet wide, with a large lump of masonry (the remainder of the pier between the 1st and 2nd arches), left standing. (See Fig. 4, showing the appearance of the wall).• 'l'he firing then ceased.

18th September.-Commenced at 8.20 A.M. to breach the right face of the detached wall in front of lunette B; the wall was a continuation of that of the flank which was breached on the pre,ious afternoon, and was of a similar construction (see section, Fig. 5). The ordnance used were four iron guns of 6-pdr. calibre, weighing 1,300 lbs., and two cast steel guns of the same calibre, ,veighing 800 lbs. All these guns were rifled and breech-loading; the weight of the shell was 13 lbs., and that of the charge ly'uth lbs.

The guns were placed in breaching battery No. 2, on the counterscarp opposite the wall, at a distance of 50 Prussian paces.

The wall was marked out into squares of 2 feet each side by white lines. 'l'be first round from each gun was directed at 6 feet from the bottom of the

wall, which was the level of the chemin-des-rondes inside. The six shells struck this line exactly, making the commencement of a horizontal cut extending about 70 feet along the centre of the space marked out; the penetration averaged 18".

The guns were then fired together in salvoes, and after 25 salvoes, or 156 rounds, including the first six, the wa11 was nearly nll cut through except at the counterforts, the height of the cut averaging 2 feet, and the depth 3 feet, the counterfort between tho 2nd and 3rd arch being more injured than any of the rest.

The guns were then directed so as to make a vertical cut upwards on each flank of the breach, three guns at each flank.

'l'~e res~lt of 4 salvoes, thus directed, was to bring down masses of the wall, more particularly on the left, the brick-work coming down in large blocks; two more sal'foes cleared away the whole of the masonry within the 2nd arch, a great part of the counterforts between the 2nd and 3rd, and between the 3rd and 4th arches, as well as of the counterfort between the 5th and 6th arches.

• These drawings are not copies of those which accompanied Lt. Col. Ross's original Report.: The latter having been mislaid, I have been obliged to make another set from roug-h sketches :md photographs.-Ed,

REPORT ON THE SIEGE OPERATIONS CARRIED ON AT JULIEilS, 103

'l'he fire was now directed exclusively against the counterforts; after 4 more salvoes (222 rounds in all) the arch No. 2 gave way, and that part of the wall was opened; another salYo brought down great part of the 3rd arch, but the counterfort between arches 3 and 4 still stood; the next salvo (38th) brought down the remainder of arch No. 3, the half of the arch with the superincum~ bent masonry coming down to the left in one large mass and resting on the top of the wall i the vertical cut on the right of the breach was also much widened and deepened. After 7 more salvoes (276 rounds in all) the remainder of the wall came down, except part of the counterfort between arches 3 and 4, and the mass to the left which was resting against it. A practicable breach 70 feet wide was thus effected.

For the safety of the men who were to assault the breach in the afternoon, it was thought desirable to bring down the two masses left standing, which two more salvoes accomplished. The firing then ceased at half-past 1 P.M.

There was no visible difference between the effects of the fire of the iron and cnstMstecl guns.

The mortar was of good quality, although of a yellow colour, and the brick­,vork very tough.

The gabions in the embrasures of the breaching battery were scarcely at all damaged; the three first gabions in both cheeks of each embrasure were pro­tected by hurdles which stood very well; it should be recollected however that the guns were of light calibre, and the charges small.

Fig. 6 shows the appearance of the wall after 23l rounds.

BREACHING THE PALISADES.

The block-houses in lunette C, and in the ditch in front of it, having been destroyed by yesterday's fire, and two practicable breaches having been made in lunette B, it was decided that these two works should be assaulted this evening at half-past 6 o'clock and lodgements made in them.

'l.'wo storming parties, with the usual reserves, were accordingly posted in the trenches for this purpose, and at a given signal a party of Sappers descended into the ditch of lunette C and fixed two bags of powder of 70 lbs. each to the palisades at the foot of the rampart, which were exploded, forming an excellent brer,,ch in the palisades.

The storming party then advanced through the descent, preceded by Sappers carrying tools to clear away obstacles, and supported by a strong covering party, which extended along the edge of the ditch, and opened a brisk fire on the storming party entering the lunette. The defenders retired; a strong working party then followed to make n lodgement in the lunette, and to perfect the communication across the ditch.

At the same time a storming party, preceded by Sappers carrying tools and ladders, assaulted the breach in the right face of lunette B, and entrred the work, getting up the exterior slope easily without ladders; they ,vere followed by a strong working party of Sappers carrying gabions and i~trenching tools. Jn 20 minute1::1 a lodgement wae formed and tolerable cover obtamed.

164 UEPORT ON TIIE SIEGE OPERATIONS CARUIED ON A'l' JULIERS.

J\lIN"INO OPERATIONS.

19th September.-A mine was sprung by the besiegers in tho gorge of lunette B with excellent effect.

21st September.-Tbe third parallel hnYing been completed, arrangements were made for crowning the covered wny by assau1t, and also for destroying _tho block•house Fin the salient of the covered way of the countcrguard by a nnne, it bein,.,. supposed that the besieged still held this point, and defended it with great obstinacy. A gallery hnd accordingly been driven for this purpose from the advanced works on the crest of the glacis, and a charge of 150 lbs. was lodged under the wall of the block-house.

The attack was made at half.past 5 P.M., nt which hour the mine under the block-house was exploded, not however with very good effect, the tamping apparently not ha,,ing been quite sufficient; two storming parties thP.n advanced, one against the block-house and covered way, the other against the palisades in the re•entering place of arms, each party supported by troops in the 3rd parallel. As soon as possession of the CO\'ered way had been obtained a working party followed, and immediately commenced the operation of crowning, which was completed under cover of the night.

22nd September.-Four iron breech-loading rifled 24.pdr. guns were this afternoon placed in breaching battery No. 2 to breach the detached wall in front of Bastion 2, and afterwards the left face of that bastion itself1 through the opening made in the detached wall.

Weight of gun ... , ..• , ••.. between 53 and 54 cwt. of ehell ........ , • . . . • . . • . . . 57 lbs. of charge • . • • • • • • • • • • . . . . . 4 lbs.

25th September.-At half-past 8 A.M., the following operations were com­menced in the presence of His Royal Highness the Prince Regent of Prussia :­

Three mines were sprung in the left face, nnd three others under the terreplein of the right face of Counterguard 2.

These mines were fired simultaneously, although they were intended for different objects i the mines behind the left face of the counterguard were to form a breach through which the work might be stormed, and the other mines were to make an opening in the counterguard, through which the right flank of Bastion 3 could be seen from the counter-battery No. 3 in front of the coun­terguard.

'l'he first named mines were successful, and an excellent breach was formed, the o!her three were not so, apparently from the charges of powder not bein~ sufficient; so that the breaching battery1 after their explosion, remained com­pletely masked, and a considerable quantity of earth had in consequence to be removed, in orde~ that the battery might open fire on the following morning.

After these mmes had been exploded, two surcharged mines of 1,500 lbs. each were fi~cd simultaneously in the positions shown on the plan, with a view of destroymg the countermines of the besieged. The craters were about 45 feet in diameter and about 10 feet deep.

Some stone fougasaes were also fired.

REPORT ON 'fllE Sll:::CiE OPER.-\TIO'N'S CARRIED ON AT JULJERS, 165

As soon as all the mioeR were exploded the troops ad,anced from their several positions to assault the breach made in the counterguard, nnd to form a lodge­ment upon the edges of the craters made by the surcharged mines.

There was a little difficulty at fil'st in getting into the ditch to assault the breach in the countergunrd, as the debris from the mine had blocked up the entrance into the ditch from the descent i as soon as this obstacle had been over­come, the Sappers preceding the storming party advanced through the descent, carrying ladders and entrenching tools wherewith to level the breach; they shovelled some earth which bnd been blown down from the parapet over the debris of the brick-work, and the stormers advanced across, but upon a very small front. As soon as they bad surmounted the breach to the level of the chemin-des-rondes, they turned to the 1·ight and left and collected in the cbemin-dcs-rondes, where they were quite protected from any fire, and when a number of men had gathered together there they made a rush up the exterior slope of the pampet.

BREACHING THE DETACHED ,VALL IN FRONT OF THE BASTION.

As soon ns the counterguard was carried, the breaching battery No. 2 opened ,vith the four guns already described against the detached wall in front of the left face of Bastion 2, at a distance of 60 yards. (See Fig. 7).

Of the first four shots that were fired, three penetrated about 2 ft. 6 in. each into the wall, and the fourth nearly 3 feet. The masonry at this point seemed rather weak, as the face of the wall peeled off round the opening made by the shell, an effect which I had not observed before.

The fire was then directed so as to cut a line horizontally about 9 feet from the bottom of the wall. The 56th shot made an opening through the wall.

After 117 shots, the wall gave way in large masses, an opening 62 feet wide having been made in it.

The firing commenced at 10 minutes before l O A.M,, and ceased at 10 minutes before 3 P.M.

The embrasures in the breaching battery stood very well indeed; the hurdles facing the three first gabions in the cheeks on each side were blown away after 15 rounds, but the gabions themselves required no renewal or repair,

BREACHING THE BASTIONS.

September 26th.-At 8.15 A.M. commenced firing frc.m breaching battery No. 2 with the same guns na yesterday at the left face of Bastion 2, through the opening made in the detached wall; also from one brass 12-pdr. nnd two iron 12-pdrs. (already described) from battery No. 3 at the right flank of Bastion 3.

There were four guns in this battery, but the counterguard had not been cut away sufficiently to enable all four to be brought to bear on the flank.

The retired flank of Bastion 3 was breached by seven rounds from the brass 12-pdr.; and the two guns which had been placed in it were rendered useless. The wall was only 4 feet thick and the brick-work was very indifferent.

166 REPORT ON THE SIEGE OPERA1'IONS CARRIED ON A'l JULIEll8,

After 41 shots from the two iron 12-pdrs. , the embrasure in the orillon was destroyed, an d a breach was made in the wall above it 8 feet high and 8 feet wide; the firing at the flank was then discontinued. . .

'l'he penet.rntion of the first four shots from the 24-pdrs. rnto the left face of Bastion 2 was from 3 feet to 3 feet 6 inches each-the distance was 96 yards.

After 163 shots, the front of the wall was completely cut away, the length of the breach being 4G feet, nnd the height outside from 10 to 12 feet. The fh-ing ceased at 3 o'clock P,M,

The annexed plan and srction (Figs. 8 nnd 9) will explain the construction and dimensions of the wall, which was said tu have been built more than 300 years Rgo, and yet the masonry was not so tough as might have been expected. In the course of the evening I went through the escarp gallery to the rent· of the breach, and observed that the inside of the wall at the breach was in some places quite damp, (almost wet,) and the mortar was very soft and friable.

The embrasures of the breaching battery still stood very well; one fascine had been blown away from the top of the cheek of one embrasure, but the gnbions were scarcely at all injured.

September 27.-At 8.15 A.M., commenced firing from breaching battery No. 3 through the right face of Counterguard 2, with the same three guns as yesterday, against the right flank of Bastion 3. '!'he breach which had been made in the orillon yesterday had been repaired with sand-bags; and hurdles were suspended over the repaired breach from the top of the wall, to try whether they would not cause the shells to explode on striking them before they hit the wall itself. 30 rounds from these guns destroyed nearly all the sand-bags, and enlarged the breach; the hurdles seemed to produce no effect whatever; the firing at thia flank then ceased.

At the same time the firing recommenced from breaching battery No. 2, armed as before, against the breach in the left face of Bastion 2.

After 40 rounds, the counterforts, which had been left partially standing yesterday, were entirely cut away, but the superincumbent masonry between the top of the breach and the top of the wall (about 15 feet high), did not appear to have been shaken or cracked in any way.

Twenty rounds more (223 in nil, including the 163 shots fit-ed yesterday) brought down a great deal of the lower part of this, and the earth began to fall through from the rampart above. 8 rounds more brought down the wall as far as the first white line below the cordon (2 feet below it). Twenty shots more brought down the cordon, and 8 shots more (2J9 in all) brought down the whole of the masonry of the wall, but the breach was by no means practicable, it being encumbered at the bottom, and for about half-way up the slope, with immense blocks of masonry ; 35 more shots were fired at these, which broke them up considerably, and moreover brought down upon the face of the breach a large quantity of earth from the rampart above, so that the ascent became compara­tively easy until within 10 or 12 feet from the top, when it became quite vertical against the retaining wall of the interior slope of the parapet. NO shots were directed against the top of the breach for fear of injuring the town. The firing ceased at 5 minutes to l P.M., 294- shots having been fired at the breach during the two days. The appearance of the breach is shown in Pig. 10.

Jl.EPOH'l' ON THE SIEGE OPERATIONS CARRIED ON AT JULIERS. 16/

RESULTS OF THE BREACHING EXPERIMENTS.

The following may be considered a summary of the breachino experiments that were carried on :- 0

Four 12-p<lr. iron guns, nnd two 12-pdr. brass guns, weighing respectively 2,700 lbs. and 1,300 lbs. throwing a conical shell weighing 27 lbs. and fired with a charge of 21\th lbs., at 800 Prussian plces• made a prncticable breach 32 feet wide in a brick wall 3 feet thick, with counterforts 4 feet thick1 4 feet wide, and 16 feet from centre to centre, the wall being 16 feet high, and built en dt'charge, after firing 126 rounds. The first six rounds fired are omitted from this calculation as they did not strike the wall, the wall being entirely concealed fl'Dm the guns.

No difference was observable between the effects of the brass and iron guns. The bursting charge of the shells was ttths of a lb. The penetration was 15 in.

Six 6-pdr. guns, four of iron and two of cast steel, weighing respectively 1,300 lbs. and 800 lbs.1 throwing a conical shell weighing 13 lbs., and fired with a charge of lT\-th lb., at 50 paces, made a pl'acticable breach 70 feet wide in pre­cisely the same description of wall as that above described, after firing 276 rounds, the battery being situated on the counterscarp opposite the wall.

No difference was observed between the effects of the cast-steel and iron guns. The bursting charge of the shell was half a pound. The penetration of the

first single shots averaged 18 inches. }'Olu- 24-pd.r. iron gw1s, weighing between 53 and 54 cwt., throwing a shell

weighing 57 lbs., and fired with a charge of 4 lbs., at a distance of 60 yds. made a practicable breach 62 ft. wide in a loop-holed brick wall 24 ft. high and 6 ft. 6 in. thick, after firing 117 rounds, the wall being seen from the battery. The bursting charge of the shell was 2 lbs. The penetration of the two .fll'st single shots was 2 ft. 6 in. and 3 feet.

The same guns, after firing 294 rounds with the same charges, and at a distance of 96 yds., made a breach 46 feet wide in a brick wall 40 feet l1igh and 12 feet thick at the foot, with a batter of about 4 feet. The wall was 12 feet thick and built en dlcharge, with counterforts 6 feet wide, and 16 feet from centre to centre, connected by two rows of arches one abo,1e another.

The penetration of the first single shots was 3 feet to 3 ft. 6 in. All the above mentioned guns were rifled breech-loaders. In concluding my report, I trust that I may without impropriety express my

sense of the cOlrrteous attention I received from Prince Ratziwill, at the head of the Engineer Department; from Lieutenant General Von Puttkammer and Lieut. Col. Neumann, both attached to the Artillery Commission, as well as from all the Prussian officers I met with dw·ing my stay at Juliers; and I hope that Major General Hamilton, C.B., Military Attache to the British Embassy at Berlin, w}lom I was directed to join, will permit me to tender him my best thanks for the friendly assistance he afforded me on eYery occasion.

A. ROSS, Lieut. Col. Royal Engineers.

• 100 Prussian paces = 80 yds. ne.nrly.

NOTE BY THE EDITOR.-It may be useful here to endeavour to compare the results of the experiments described in Papers I and XVII, with those obtained from similar ones made at ,voolwich in 1824 and at Bapaume (see page 91 of the Corps Papers), as well as with the average calculated by Sir "\V. Denison for the breaching operations recorded in the "Journal of Sieges in ...,. Spain; " and these are shown in the following table ; but it is to be regretted that we have so little information about the nature &5 of the masonry in most cases as to render it difficult to make a complete comparison.

Weight of Nature Dishnce Tot.al weight Width projectiles No. of Place. Nature of wall breached, of or projectilea of "" Ordnance, Battery. fired. bre:i.ch. foot Jioeal of breach.

----I Smooth bored. Spain. Rubble revetment • 500 yds. 254,400 lbs. 100 ft. 2,544 lbs.

2 Do. Metz. Good rnbble revetment 20ft. high, with counterforts. 34 ,, 9,040 ,, 100,, 90 ,,

3 Do. Bapaume. { Revetment with counterforts, 36 ft. high a.nd 10 ft. thick,} 53 ,, 3,888 " 72,, 54 " i.e. 8 ft. 6 in. of chalk, and brick facing 18 in. . .

4 Do. Do. { Casemated flank, the front wall of which was 11 ft. thick,} 85 ,, 4,704 ,, 80,, 157 ,, i.e. 9 ft. 6 in. of chalk, and brick facing 18 in. . •

Ii Do. Woolwich. { Independent brick wall, 7 ft. thick between the piers,} 500 ,, 660,100 ,, 100,, 6,601 ,, and 21 ft. high. • . • • . . . • • • . • .

6 Rifled. Eastbourne. Brick Martello Tower-wall only (6 feet thick) . 1,032 ,, 2,953 ,, 20,, 147 "

7 Do. Do. Ditto ditto wall and arch. 1,032 " 10,850 ,, 24,, 452 ,,

8 Do. Juliers. { Counter-arched full revetment40 ft. high and 12 ft. thick} between the piers. • . • • • • . • • • • • 06 ,, 16,758 ,, 46,, 364 ,,

9 Do. Do. Independent brick wall 24 ft. high and 6 ft. 6 in. thick. 60 ,, 6,669 ,, 6!" 107 ,,

10 Do. Do. { Independent counter-arched brick wall, 3 in. thick} 40 ,, 3,588 ,, 70" 51 ,, between the piers, and 16 ft. high . • • • . . .

II Do. Do. { Independent co~nter-arched bri~k wall, 3 ft. thick} 640 ,, 3,564 II 32,, Ill ,. between the piers, and 16 ft. high. • . • . • .

RUlfARXS. -The fire was direct in all cases except N os. 5 and 11, in which the walls were completely hidden from the batteries, the inclination to the horizon of the lines of flight of missiles just clearing the protecting mass of earth 11nd striking the wall Jow ~nought~ effect a breach (i.e. their "terminal angles" J being in the latter case 5°. It may here be remarked that this angle 1s very different from the terminal angle at which missiles must strike a kaponier placed in a narrow ditch, and so that it cannot be breached except by those which pass close to the crest of a glacis at a distance of only 50 feet in front of it and 25 feet above the point required to be hit, as the terminal angle must in that case be about 26°; and experiments are tl1erefore needed to prove the effect of elongated missiles especially, fired under such circumstances necessarily with ~ery reduced charges.

" ~ 0

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REPORT ON THE SIEGE OPERATIONS CARRIED ON AT JULIERS. 169

Nous ON THB EFFECT OF SIIELLS FIRED FROM RIFLED GUNS AND WALL

PIECES AGAINST SAPS, &c.

September 21.-Experiments were carried on this mornino- with a view of test!ng the effects of the Prussian 6-pr. cast-iron breech-lo;d.ing rifled gwi, agmnst approaches and parallels.

For this purpose, portions of the followi.ng kinds of works had been con­structed in a line, in a convenient position at the foot of the rising ground on the north side of the fortress.

lst.-An um·evetted or Turkish double sap, as it was termed. 2nd.-An ordinary double sap revetted with gabions, with one row of fascines. 3rd.-A single sap lined with sand bags. 4th and .Sth.-Portions of second parallel revetted wit,h gabions, and crowned

vdth three rows of fnscines. 6th.-Another portion of sap similar to No. 3. 7th.-Two common gabions filled with earth. Sth.-Two gabions of sheet iron ,\,th inch thick, filled with earth.

Deal planking was placed immediately in rear of each, to shew the effect of any shells or s1Jlinters which might pass through.

The sap-rollers were stuffed with f'ascincs a11d had a wooden head at each end. The guns were placed at 1,000 paces from this line of works. The weight of

the shell was 13 lbs., that of the charge 1 ·2 pounds, and the shells were exploded by means of concussion fuzes.

Several rounds were then tired from the guns at the earth-works (but not at the gabions.)

The single sap appeared to offer very little resistance, the shells bursting in their passage through it, dislodging the gabions and sand bags, and the splinters shattering the planking in rear.

The double sap was not so much injured in the first instance, but after three or four rounds the splinters of the shells came through, producing considerable effect on the planking, as well as on the reverse side of the sap.

The unrevetted or Tw·kish double sap resisted the fi.l'st round, which was however fired rather low, and probably struck the ground under the loose earth. The second round however penetrated, and the splinters of the shell struck the planking.

The portion of the !econd parallel resisted the first two shells, but afterward:-1 the splinters penetrated through into the planking, as in the case of the sap.

The deal planking shewed that no men could have lived in these trenches while the fire was going on.

The gabions, both iron and common, were then fired from at a range of 450 paces, with two wall pieces, or " amusettes," as they were termed, carrying au elongated iron projectile, weighing about 1 lb., its diameter being l ·35 inches. These pieces are short breech-loaders, 3 inches of the breech only being rifled with four grooves, and having one tw·n of the spiral in six inches. They were fired from the shoulder, being fitted with springs to check the recoil, and were ignited by a needle, like the ordinary Prussian musquet. The ball is encased in thick cardboard, to make it fit the rifle grooves.

The shots from these pieces all penetrated both descriptions of gabious, except in one instance, where a sheet iron gabion was struck fairly in the centre, and the shot did not penetrate it.

A. ROSS, Lieut. Col, Royal Euginecr•. y

I ,.

liO

EXTRACTS Fnmr THE REPORT OF CAPTAIN GIESE,

PRUSSIAN RoYAL ENGINEERS;

TRANSLATED BY MAJOR GENERAL HAMILTON, C.B.•

DEMOLITION OF TIIE WORKS OF THE TOWN OF JULIERS.

The charges were placed by means of shafts sunk from the banquettes, and were so regulated as to be just sufficient to throw down the scarp revetments without endangering the town in rear or the ground in front. Twenty pow1ds of powder were allowed for u each foot of least resistance," or 200 lbs. for a line of least resistance of 1 0 feet. Fifty feet of hollow space were left in each chamber to increase the effect. The JJowder cases were inserted in the counter­forts, ancl two feet above the level of the ditch.

'l'hc first tamping of each mine was close to the counterforts, and was effected by means of strong beams. This operation was repeated at each turning of the gallery ; and between two turnings the tamping was strengthened with moist bods, which "·ere forced in up to the tops of the galleries and shafts.

Four non-commissioned officers, 30 sappers, and 16 labourers1 performed the whole tamping in eight hours, using 530 cwt. of materials.

The ignition was effected by means of two gah-anic batteries of 72 cells each, joined together ; six of the mines were fired simultaneously. The commw1ica­ting wires were isolated in the tamping by means of gutta percha.

BREACHING TlIE LEF'r FACE OF COUNTERGUARD 2 1 BY :i\fINING.

This was effected for the 1m1·posc of making a lodgement on the counter• guat'd at a distance of 18 yards from its salient.

Three mines were formed, as shown in Figs. 11 and 12. They were fired i:,inmltancously, and a thoroughly practicable breach 18 feet broad was made.

l\IINE OF DEMOLITION TO OPEN THE RIOHT FACE OF THE COUNTERGUARD,

SO AS TO UNMASK THE COUNTER-BATTERY.

The quantity of powder calculated to be necessru:y, viz., 30 centncrs (cwt.) in eight mines, (3 on each side and 2 in the middle), was reduced to 12 centuers in tlu·ee mines, with the view to the greater safety of the buildings in the citadel and the town. Three galleries were driven from the lodgement made in the counterguard, in an inclined direction, and a charge of 400 lbs. was lodged at the end of each, the intervals between the charges being 26 feet.

Owing to the smallness of the charges, the parrtpet only was thrown down, and the terreplein slightly lowered, so that only the upper part of the wall and the cordon of the distant flank could be seen from the battery.

During the night, the co1..lTiterguard was lowered 6 feet by the sappers, so that the sills of the embrasures of the flank could be plainly seen from the battery.

• We have to thank General Hamilton both for obtaining antl tl'anslating this Heport-E11,

REPORT ON TIIF. SIEGE OPERATIONS CARRIED ON AT JULIERS. 171

EXPLOSION OF TWO SURCIIARGED MINES.

From a lodgement made in a prcYiously formed crater, t'wo inclined galleries were driven forward, and two charges, each of 15 centners (cwt.,) were placed 18 feet deep. They were fil'cd by means of galyanic apparatus, ancl they pro• ducccl two craters, respectively 50 and 56 feet in diameter, 97 and 10¼ feet deep, and 2-1 feet apart. The mass of earth was t,hrown upwards to the height of 60 feet.

EXPLOSION OF FOUR STONE FOUGASSES.

These were consfruc.tcd in tl1c covered way, on one side of the block.houses which were to be stormed, and were directed against the craters of the mines, nnd against the su1iposed column of attack. They were each charged ";ith 20 lbs. of powder, and 20 stones about the size of the fist. The II cone of dis• pcrsion" of each was about 100 paces long and 60 to 80 paces broad.

FlRING AGAINST AN EARTIIEN BATTERY.

The guns were placed near to, and in front of luuette C, and were directed against an enfilading battery on the ~Icrtchen Heights, on ground 50 feet higher and at a distance of 1,150 paces. The battery was at a considerable angle with the line of fire.

Two 24-prs. ancl two 12-prs. fired eight shots each, after which two em~ brasures were rendered temporarily unserviceable.

Two 6-prs. fired eight shots, which produced little effect on the third em~ 'brasure.

Two G-prs. fired five shots more against the same embrasure, without pro-­ducing any considerable effect.

FIRING AGAINST A PARAPET OF SAND BAGS 7 FEET THICK AT THE TOP.

Shells were fired from a 24-pr. with a charge of 4lbs., at a range of 1,150 paces, the bursting charge being 21b. Out of 10 shots there were 7 hits. The sand bags were knocked off to the depth of 2 feet. Some of the fragments of shells penetrated 7 feet. The sand bags were thrown 20 feet high, and 40 paces distant from the parapet.

CROWNl~G THE CRATERS OF MIXES BY SAPPING.

The method hitherto employed for crowning the craters with ga.bions does not now appear to answer the pw·pose, for the gabions are no sooner placed than they a.re easily thrown oYcr, and the crater itself could not be held under a continued shower of shells ancl stones.

In consequence of the experience gained at Sebastopol, it appears necessary to have recourse to another method in effecting such lodgements. Every two sappers work together, standing against and protected by the inner slo1)e of the crater, ancl about 7 feet below its upper edge. (Sec Figs.13 and 14.) They throw the earth to each side of them and to the front. Having reached the edge of the crater, No. 1 sa1lper turns to the right, and No. 2, as soon as there is room for him, to the left, until the sap and breastwork are completed along the whole of the front of the crater. The trench in which the sapper works -viill be made at once of the width of l ½ to 2 feet, and will afterwards be widened. The depth will he rcg1tlatcd nccord-ing to the cover that is required.

I

1

172 REPORT ON THE SIEGE OPERATIONS CARRIED ON AT JULIERS,

PASSAOE OF THE WET DITCII.

Fascines were thrown in up to the level of the water; and on the top of these, to render the surface level1 sand bags were thrown. These were also employed to form a "blindage" to cover the front, and to strengthen the exterior of the two lnteml breast.works, which were formed of two double 1·ows of gabions, leaving a clear spare of from 7 to 12 feet between them. (See Fig. 15.)

The fascines were 6 inches thick, 4 to 6 feet long, nnd had three bands. When weighted with bricks, which were enclosed inside them, they weighed 30 to 35 lbs. each, and could be easily thrown by one mn.n to the front or to the sides.

A gabion filled with brushwood, and weighted with three stones, weighed 87lbs., and would float. ·when they were completely filled with stones, they of course sank, but owing to their bulk and t.he irregular positions which they took up when thrown oYer, they were found to be of no use in forming the dam.

The sand bags, which weighed from 25 to 35 lbs., could be thrown backwards over the head, and over the front parapet.

During the progress of the work, a breast-work of sand bags covered the opening from the descent into the ditch. Two or three men were simul­taneously employed in throwing over this breast-work, to the front and to the sides, as many fascines ns were sufficient to raise the dam for several feet in length to the le,el of the water.

The sand bag breast-work is then gradually advanced, by throwing the sand bags over to the front, so that a gabion may be placed at each side. The fascines, which have been hitherto lying one over the other in an irregular manner, are, upon the advance of the sand bag parapet, pressed together, enough of the sand bags being left on the top of the dam as are required to bring it to a level above the surface of the water.

PENETRATION OF TIIE PROJECTILE FIRED FROM THE NEW WALL PIECE"'.

Experiments were made with iron gabions, the diameter of which was 21 inches, and height 30 inches. The thickness of the plates was ,r\ inch, and the weight was 26 to 28 lbs. They were made of two half-cylinders fastened together by bolts.

At 400 paces, the penetration into these gabions, filled with earth and gravel, was 16 inches. 'l'he shot never penetrated the centre at 400 paces; and at 150 paces, when the shot struck the centre it only penetrated to the opposite side of the gabion; whilst the common gabion was shot through at 400 paces.

FIRING AT LOOPHOLES TO DETERMINE TUE CHANCES OF HITTING THEM.

1st, against vertical loopholes, the interior openings of which were 12 inches high and 4 inches wide, with the needle musket at .50 paces, 10 shots and 10 hits, and at 200 paces 10 shots and 5 hits .

. 2nd, against horizontal loopholes,_the opening being 36 inches long and 4 inches high, at .50 pa~es, 10 shots.an~ _4 hits, and at 200 paces, 10 shots and 4 hits.

The conclusion wa~ preJud1cial to _the use of the vertical loopholes, in conse• quence of the very shght lateral deviation of the balls.

• Thi, ia the" amusette" r~ferred to by Lieut. Col Ross. ( See page 169). -Eo.

I PL I.

:~ . . I I

V

-

) '-.I

Bast

l /

-j

INDEX TO TB&

YOLUMES OF THE PROFESSIONAL PAPERS AND CORPS PAPERS

PUBLISIIED SINCE TBE FIRST INDEX WAS PRINTED, IN 1845,

JN TilE 8TH VOLU:\IE OF THE QUARTO SERIES.

N.B.-The principal words in the title of each Paper must be looked for on the left of this Index. The letters C. P., standing in place of the number of the

volume, indicate the "CORPS PAPERS," published in three parh in 1849-.50; nnd the letter Q distinguishes the volumes of the" QUARTO SERIES," published previously.

Agulhas Lighthouse; construction. Alderney Breakwater ; use of concrete in it ..... ,

Do. do. barge used there ............. . Aldershot; stabling for temporary purposes ........... . Alexander, on storms on the Atlantic .............•.•.• Ali wal ; plan of the battle . . . . . • • . . . . • • . . . • . . . . . .. Ahwah; account of the siege . . . . . . . • .......•......• Arch; remarks on its equilibrium, by Lieut. St. John ... . Do. form of voussoirs, by the Rev. J. Twisclen ...... , • Armstrong guns; breaching power ..••.............. Arthur's seat; deflection of the plumb line, by Sir II.

James, RE ............................•...... Asphaltc, as used at Plymouth and Cologne ........ .

Do. ·employed in cold climates, by General SaYago and Captain Parsons. . . . . . . . , ... , .. , ...... .

Do. notes on its use at Plymouth, by General Oldfield Atlantic telegraph cable laid down in 1857 ..•..... Authors on military science i Italian .• , •• , . , .....•...

VOL.

I. II.

III. VII. III.

Q. X. X. I.

X. x.

VI. III.

IV. V.

VII. C. P.

PAGE

46 129 149 88

196 156 41 63 11

1

149 1:32

85 .:;3

99 63

ii. CONTENTS OF VOLUMES.

Baking in pol'table ovens at Woolmer Camp Bapaume; experiments in breaching and mining ..... Barge used in forming the breakwater at Alderney .. Barracks; construction of, by Sir ,v. Denison, R.E ..... Barrack; loopholed, at Pembroke .....•.....•..•.... Barracks at Forton, near Gosport ..•.. . ..••.•... .. ... Barricades in towns; by Sir John Burgoyne •• •••• ..••

Do. do. do. Do. do. effect of guns in casemates

Batteries for the defence of coasts; by General Yule, R.E. Do. do. do. do. Do. do. do. by Lt. Col. Bainbrigge Do. do. do. by Colonel Nelson ..

Bermuda; remarks on gale in 18.52 •••••••••..••.....

Blasting rnck at Holyhead in 1850 ......•... , ...... . Do. do. in 1857 .................•

Do. do. in 1860 . ................ . Bomarsund; operations against the forts, in 18.54 ••••••

Do. demolition of the forts by the French ..•..• Do. do. by the British .....•

Boundary of United States; account of the survey •••••• Do. do. do. do.

Boundary of Canada and New Brunswick.... • ••.....• Do. do. do. . ........... .

Brailow; account of mining operations at siege in 1828 ..

Brandreth i memoir of Colonel Brandreth, R.E .•••....• Breaching a wall at Portland with 68-pdr. shot ....... .

Do. a tower near Eastbourne with Armstrong guns Do. a parapet at Berlin with shells .. , ...•..... , . Do. Do. Do. Do. Do.

a merlon of masonry at Gibraltar ..••••• , •.•. stockades at Chatham ....... , ...• , . , .... .

do. do. walls at Bapaume in 1847.., ..... , ...... .,.

do. at Chatham in 1848, ..........•.•.... Do. a casemate in Germany ................. . Do. scarp walls with rifled guns at J uliers •.••••

Breach in embankment at Foulness; report on repairs .• Breakwater of floating spars, proposed by General Yule,,

Do. at Alderney, use of concrete in it ........ , . Do. of diamond~sha.ped piers, by Gen. Cole, R.E. Do. effect of waYcs on breakwaters, do.

VOL.

IX. c . .P.

III. C. P.

Q. VIII. II.

C. P. C. P. C. P.

V. C. P.

IX. VI. III. II.

VI. X. V. V. V.

C. P. C. P.

III. IV.

VII. Q. X.

IX. X. V.

IX. C. P.

IV. C. P. C. P. VII.

X. C. P.

Q. VIII. II.

III. ff.

PAGE

15 80

149 247 39

101 398 408 3.;9

81 101 66

119 196

1 140 28

I

19 25

107 273

70 1

I

44 45

221 51 80

221 42

169 415 82

129

119 95

CO:STENTS 0~' YOLUMES,

Bridges oYer the Gogra and Chowka rivers .....••.. , • Do. notes on drawbridges, by General Lewis, R ,E •.• Do. across the Shannon; demolitions in 1844

Bridge of St. :Martino near 1'1ageuta; blasting • .'.'.'.'.'." Bridges; construction of suspension bridges, by Col. Harness Bridge at Canick-on-Shnnnon • demolition Bridge at Bnllec Khal; failm·: in June, 184; •: _. _. ." .·.·:.-: ~ Bridges ; construction of suspension bridges, by Colonel

Goocl"'}'n •...••.•..•.••.•••••.......•. •. ....•

lluilding at Hong-Kong .. , , • • • . • . . • • ....... . ..... .

Bulk of commissariat provisions ... , • . . • .••.... • 0 • • , • •

Canada boundary ..••.•••••....•.••••••.•..••.....•

Canal from Bay of Fundy to Gulph of St. Lawrence-survey Cannon ; construction in Arsenal at ,v oolwich ...•...• Canton; demolition of forts in 1847 ................. .

Do. laying down electric telegraph in 1858 .......• Do. demolition of forts in 1858 ....•....•••••....

Cape of Good Hope; survey by Mr. Hemming ...•.•.• Carbine of the Royal Engineers-penetration ....•••••.

Carbonization of wood by steam . ..... . . . . . . . . . . . . .. . Carpentry applied to roofs, by General Woddii1gton .•.. Carriages fo1· coast batteries, by General Yule and Captain

Fowke, R.E .................................. . Casemate-embrasures; report on experiments made nt

West Point in the State of New York in 1852-53-54,

and 55, by Brigadier General Totten ...........• , • Casemo.tes; effect of guns in casemates •••••••..•..•..

Do. accumulation of smoke in those at Chatham and New Brisack ••••••........•.••.... , ...... .

YOL.

X. C. P.

Q.VIII. X.

Q. IX. Q. IX. Q. IX.

Q. X. Q. X.

C. P.

Im. IV. Q. VIII. Q. VIII.

II. VIII. V!II.

I. VI.

C. P. Q. X.

V.

VIII. C. P.

V.

iii.

PAGE

38 396

116 145 79

83

189

153

414

186

42

93 98

75 27

16¾

203 71

81

359

39

CO~TRN'l'S Of VOLU:llES.

Casemates; experiment on breaching one in Germany

Do. on the escape of smoke from those at Donr

after firing . . . • . . . . . . . . . . . . . . . .............. .

Casemates ;-on the escape of smoke from thoee at Cliff-end

Fort .. .. , ........................ . Cawnpore; memorandum on the three passages of the

Ganges at Cnwnpore in 1857 . . . .... Cement discovered by Captain H. Scott, R.E .....

Do. clo. manufacture described

Ceylon government railway survey ....... .

Do. road-making, by Captain Schaw, R.E ......... . Chapel for the garrison of Dublin .... Chatham; siege operations in 1848 ............... . Chimneys cured of smoking, by I\fajor Hassard

Chimney at Steam Factory in Woolwich Dockyard. • ... Chinese infernal machines • • . • . . . . . . . . . . . . . . . . ..•.•

Chowka river; construction of bridge ..... .

Circassia; operations on the coast in 18.54 ... .......... .

Coast Batteries ; by General Yule, R.E . .............. . Do. by Sir John Burgoyne ............. , Do. do. Do. Do.

Coast Defon ccs ; Do. Do. Do. Do. Do. Do.

by General Lewis by Lieut. Col. Bainbrigge . , . , ..... , .. by Sir John Burgoyne ............ .

do. by General Lewis

do. by Sir John Burgoyne by Colonel Nelson by General Yule

Do. by Lieut. Col. Bainbrigge

Coast defence of England; by the Baron M. de Sellon .. Do. do. remarks by General Lewis , .

Do. clo. do Coffer-dam at Devonport Dockyard .. , ............ .

Colby i memoir by General Portlock-at commencement ofVols ............... .

Columns of iron; practice against them in 1846 ... .

Commissariat provisions; bulk ..................... .

Convict labour in ,vestcrn Australia ................ .

VOL. PACE

VIL 42

IX. 13

IX. 46

VIII. 106 VI, 143 X. 132

VIL 8 VI. 121 II. 2,j

C. P. 217 VIL 137

Q. IX. 70 IX. 48 X. 38 V. 99 V. 81

C. P. 101 C. P. 408 C. P. 359

IX. 66 C. P. 101

I. 1 V. 111 II. 105 VI. 115 VI. 119 V. 81

IX. 66 II. 105 II. 125

Q. X. 36 Q, VIII. 61

III., IV., V. V. 65

C. P. 414 VIII. 116

C'U.S'l'ENTS 01 YOLUilH:.S.

Corfu i failure of masonry at Fort Neuf in 1844 . ~. . ...

Do. inclined plane and stretched ropes used on the works Do. siege in lilG ..................... . ........ .. Crimea; French troops and material sent thither in 1834

and 1856 ·················· · ········ .. .. Cyclopean walls in Santa l\Iaura

Dam at Devon port Dockyard . .. ...... ....... Danubian Principalities; topographical notes ... Dawson; monument to Capt. Dawson's memory in Ceylon Demolition of Fort at Ruttunghur . .. ····· ····· ···

Do. bridges o,er the Shannon in 1844 .. no. bridge at Carrick-on-Shannon in 1845 Do. Forts at Bomarsuud . . . ...

Do. Forts at Canton in 1858 . . . .

Do. do. in 1847 ...

Do. Docks at Sebastopol, by British Do. do. do. by French .. Do. White Barracks at Sebastopol

Do. Fort Nicholas at Sebastopol

Do. works at Bapaume . ... Do. stockades at Chatham ..

Do. do. do.

Do. wall at Chatham .. Do. houses at a fu-e in Edinburgh ...•

Do. do. do. in Montreal

Do. magazine at Halifax: . ..

Do. Rochester old bridge in 1856-7

Do. do. do. in 1857

Do. do. do. in 1858

Demolition of Fort of Tutteah ... ···················· Do. Fort at Furruckabad . ....... ·········· Do. Bridge of St. :Martino near :Magenta . .....

Do. Scarp walls aud palisades at J uliers

v.

YOL, PAGE Q.VllI. 76

IV. 6:l C. P. 262

VI. 59 C. P. 21

Q. VIII. 61 IV. !OJ

I. 67 IX. 7

Q. VIII. Q. IX. 79

V. 19 YIU. 98

II. 93 YI. 21 VI. 83 H. 53

VII. 136 C. P. 80 C. P. 221

IV. 51 C. P. 221

IV. 58 IV. 54

C. P. 214

YII. YIU. G3

IX. 39 VIII. 64

VIII. H X. 116

X. IJ3

vi. CONTEN'fB Ol' VOLUMES.

Dialling; note on dialling, by Lieut. St. John, R.E. Ditch-passage of wet ditch nt J ulie1·s .....•....... Diving apparatus of Dr. Pnyerne Dockyards j-works for their defence, by Lt. Col. J ervois Drawbridges; comparison of different kinds .....•....

Do. at Bern1uda.. • • . • • ••••.•..•...•....• Drawing-boards; Jiir. Howlett's construction....... . . Dredge suspension bridge; inquiry into the principle Duties of' the officers of Royal Engineers, by Col. Nelson

Earth; projection by Sir H. James, R.E .. Do. on its figure, dimensions, and specific gra:fity as

deriYCd from Ordnance Survey . . • . . . . . . . Do. do. do. Earthquakes; construction of buildings for security against

the effects of earthquakes ............... ., ..... .. Do. do. do. Earthworks in fortifications ....................... . Eckernf0rde ; attack of batteries by the Danes Edinburgh; demolition of houses after the fire in 1824 .. Electricity; notes on its application to the explosion of

mines, by Dr. Figuier, ?\:1. du ~1oncel, and Major Von Ebner Go •••••••••••••••••••••••••• ' ••••••

Electricity; application of Voltaic battery, by Captain Ward, R.E .................................. ..

Do. do. by Captain H. Scott, R.E. Do. Report by Professor Wheatstone and Mr. Abel .... Elson; failure of scarp wall of fort .........•.....•.. Embrasures in casemates; Report on experiments made at

West Point, in the State of New York, in 1852-53-54 and 55, by Brigadier General Totten .......•.•

Embrasures; projects of General Yule, General Thomson, General Sandham, and Captain Fowke, R.E. . .....

Embrasures; on construction of embrasures, by Captain Penrice, R.E ..•.•.. , ...••••••••••...•.........

Enfilade fire; experiments at Berlin .........••.....• Engineer officers' duties and studies; syllabus .....•.•.• England; defence agai.urst invasion, by General Lewis

Do. do, do. do,

YOL,

I. X. V.

IX. C. P.

Q. IX. V.

c. I'. VII.

VII.

VII. VI.

I. I.

X. C. P.

IV.

VII.

IV. VI. X.

IX.

VIII.

V.

Q. IX. V.

VII. Q. IX. Q. X.

PAOE

50 1J9

35 129 396

40

l!J 24

130

134

111 149

12 120

126

408 58

139

111 166 89 64

81

149 44

130 20 36

CONTENTS 01~ VOT.UMES.

Fnnshawe; memoir of General Fanshawe .... , ...... . Fttseinc-founclation used for a battery near Stettin ... . Fcrozeshah; plan of battle ................... . Fire at I\lontreal in 18.j2; mode of checking it ... . .. . • Do. at Edinburgh in 1824; demolition of houses Do.-protection of wood against fire, by Mr Abel .•. Floating stage at Rochester Bridge ...........•. Floors; on fire-proof floors, by Captain Fowke, R.E. Fortification, with reference to the use of rifled weapons,

by Captain Tyler . . . . . • . . . . . . . . .... . ..... . Fortification ; influence of improvements in the arms in

use, by Major Ewart, R.E. ..................... . Fortification; improvements in permanent fortification,

translated from the German .. . .. Fortification; project by Colonel Nelson, R.E.

Do. do. by Lieutenant Colonel Bainbrigge. Do. of the United Kingdom, by Gen. Thackeray Do. on the principles of defence, (Part I.)

by General Portlock ............ . Do. do. (Part II.) .............. ..

Do. in Germany; memoir by Captain ~Iangin .. Do. of England, by Lieut. Col.,Vestmacott, R.E. Do. remedy of defects in systems, by do.

Fortifications ; influence on warlike operations, by General Lewis ...

Fortification of Dockyards, &c., by Lieut. Col. J ervois .. Forton; additions to ~Iarine Barracks ............ . .. . Fortresses; observations on their value, by Gen. Lewis ..

Do. analysis of their value, by do. Do. report on their condition, ordered by Napoleon I.

Fougass, fired nt Chatham in 18J3. Foulness; repairs to embankment Foundations of works in India ..................... .

Do. formed with wells .... . Do. of fascines used for a battery near Stettin .. Do. defects of Fort Neuf, Corfu ......... .

French troops and material sent to the Crimea in 1854-and 1656 ................................ ..

Furruckabad; demolition of Nawab'a Fort in 1858 ..... .

Yii,

YOL, PAGE

IX. 62 IV. 78

Q. X. 156 IV. 54 IV. 58 V. 102

YlII. 62 X. 8

IX. 3;

VII. 47

YI!. 37 I. 14

Q. IX. 35

I. 96

C. P. 39 C. P. 362

III. 167 IV. 09 v. 54

YI. 31 IX. 129

II. IOI Q. IX.

YI. 110 II. g5

. IV. 80 C. P. 415

I. 56 C. P. 50

IV. 78 Q. YlII. 76

YI. 59 VIII. 44

Gamons made of iron pbte<, by 0.p:ain H. Tyler. R.E Do. of hoop iron; report by Lieut. Fnuil.bnd. R.E.

Gmi.e - ; JJd:,61- ~ or :he ri~er a! Cawnpore in 1 ~; ...•• Geo o;y; rt'?!:.:rrk:s on the use or tl:e _ -ienee, by Colone!

Bami Smith ...•..•.•...... Georgia; operatio~ on the ~! in 1 • » ...... . ... . . Gozra R.:..-er; oon.,--n-cction ofbri<L"t' .....••..•.•.•.. Ge-~ !°o':.Dd in the A~-:ral.ian rol;~ies i no"ts by Sir\\·.

Deni:.on .• • ...•.... • .

Great B!:~ F:ea.!!!.er; node or !"f::le3..illl.? her­Gro:!:3 !or protection of redonb;; near B y~e ... Do. on the C'CJ85: c: s~~::s: Do. a: Sa:::d;51e Ca.s;Le ............•..... . ....•

Do. :1: Eas:bmrr-..e and Hy-..he . • .. . .. . . . .......• G:mpow-Cer i.I:.'""El!ta! by JL _.\.ng-E:i~ .....•.....•

G~powill; co~--u-n.J:":i'l!? o!bcil~ fur::£ =i.a.nu!ac:are

Do. 2!pp:.:ca::::J.:: ar:: proposed by C3pt. Pe:!.r...ce ••

Ha:.:.:'.u: C:adcl; d.e:m1:X..o:n o!!2~~ :!I IS-!; Hal::n: a111: Q,,ebec P.a.i:~.,, fuprr: by Co~ P.olr...c.,,:i..

Ho!y~C i acc:oo.z: o! t!le ~ c~ qua...~-~ :!11L--.e :!:.ere i.:,. 1:;o .. . . . . . . . . . . . . . . . . ............... . .

H~:y~d; b2..li:::.n.g .ri:.h 1? ~ in ::-:t; .•...•. Do. 6. i!n. :r1 : ~60 . . . . . . .

H.o:1_;-R!ru~; m:;·d;....: ~ .!:lD.ll: ui ~g ..,,.~..qh:.:. at

Ho:,;;-Kc::,; . .. ....•.....•.. H~~ :::1 t!:e ~..=ea; &por: G:' a Boar.! O!l t!:.e EDbject H~-~..a.b:es a: _\.!rl.e~c.: • . . . . ....•. . • - . . • • . ....••

Hy~~__c o~~~ .. by !iftcl"!l3..:..: Re-...:iy~ R.E.

bcl!nee!. pla::.e a: Co!'fu fcr n,.iM: ma:.er...:ib ■• • • • • ••

IE~ =iacl:!mes t;_--00 by :hf'. C"-~ • . . • . •• .

l.: .:I: E~i!CG o: ~e 5CJ,~J.Ofu (l!l :',:~ :.._1"("!1 .••• , , • , ••

L"O:o co:.,,,,,,,, cl ,;la:es; pnctice 3="1in.,-: :he= :n l '>M.

1:aEx: a=-...~ c-= =.iiry =C..EI!..."!'1 by Ge:e,~ Pc:-...:.ock...

T!:.'!!!£; aero--=..: of ::M F..e-;e !!: 15-:;- ••••

J tiliers; ~ of c-pe:r:t::n=s :U ~ YY.l ......... . .. u ••

fu hruc!:i,,g .a!Js . . • . . . . . . . . .••...••.. . .

Jk. ==ri=? Cpc3t=..! ••• , • ••

TOL. \'.

\'.

\'111.

C. P. \"

:s..

m. Q. :s..

L C. P. C. P. ill.

L 1L

C. P.

c. P. 1L

Il. n. :s..

Q_ :S..

HI. \ll.

\'

IY. J.X_

c. P.

'· (. P.

:s.. :s.. :s.. X.

Pl:3£

93

~l

lM

103

49

6;

00 -w; J,'.,2

95

91 ;3

~H 3-l

l

14() ~

1-'.l

53 ,-.;,;

6-:-i -1,

!l)r,

&,:;

62

33 159 i.;~

I ;J

CONTENTS OF VOT.UMES,

K 'lrs ; construction of ite defences, by Colonel Lake .... Kertch ; notes on the works con;tructed by l\Iojot'

Stokes, R.E. 1 in 1855-6 .........•••.•...

Kinburn i Journal of operations in 1855 ............. .

Ladders formed into a tripod for observations ......... . Lancaster carbine; experiments on penetration .......•

Do. do. do. Landing-stage at Rochester Bridge ..•• , •••........ Lead; contamination of water in ci~terns ........ , ••... Le"elling instrument constructed by Messrs. Elliott Lighthouse at Agulhas; construction. Lime in,ented by Captain H. Scott, R.E ...••. Loopholes at Aden, by General lVaddington Loophole of metal to reYolve . . • • . . ...•......•.• Loopholes; consfruction proposed by Colonel Alderson ..

Do. do do. by General Ord ..•.•. Luck.now; Reports on the defences in 18,jS ....••••..

Do. Reports ou the defence in 1857 ....•....... Do. Reports on the siege in 1858 .... , •••••.•.•

Lyon is; description of the forts •........•...•.•.....

:\fag:ieto-electric:ity; Report by Profe~sor ,rhcntstone nnd

Mr. Abel ······· .... ...... ·················· Martini; Notice of his works. by Colonel Ty Iden . . ......

:\'Ie::i.nee; account of tbe battle, by General ,vaddington ..

Do. remarks on the account of the battle by do.

Do. do. do. by Sir ,v. Napier ..

Do. do. do. do.

:V[eteorologico.l observo.tions i arran;cments for making

them .... ... ······················· :\-Ieteorological obsenations, by Sir H. James, R.E .•.•••

Do. do do.

:Jining operations o.t Chatham in 184--1: ··········

be.

YOL, P.\OR

YI. 96

Yl!I. 34 VI. 130

YII. 44

nc. 155

VI. 16{

Y!ll. 62

IX. 4;

YJI. 137 I. 46

X. 132

C. P. 19; V. 70

Q. YIII. i8 Q. VIII. 80

IX. Jj

X. 48

X. 67 Q. IX.

x. 89

c. P. J ;o Q. IX. 25

I. 87 III. 126

Q. X. 66

I. 101

I 11. 202

IV. 75

Q. VIII. 156

x. CONTF.NTS OF VOLUMES:.

VOL.

Mining; plans proposed by Capt. Penrice. Q. VIII. 181 and C. P. l\'lining; application of electricity in France and Germany VII. lllining at Juliers in 1860 . . . . . . . . . . . . . . .. . . . . . . . . . . X. Mining operations at Bapaume in 184 7.. . . . . . . . . . . . . . . C. P.

Do. in Phamix Park, Dublin........ . . . . C. P. Do. at Chatham in 1848 . . . . . . . . . . .. . .. . C. P.

Do. at Seaford .................•.... Do. at Schweidnitz, Silistria, and Brailow;

and in Germany ..••••....•••..•.•............

Montreal; great fire in 1852; mode of checking it ..... . l\Ioultan; account of the siege in 1848-9 . . . . . ..••..••

I.

VII. IY.

C. P.

N asrnyth's steam hammer ...•.....•.•.....•...••••• Q. VIII.

Do. steam pile-driving machine ...............• Q. VIII.

Natal; defence of in trenched camp in 1842 .......... , • Do. notes on the settlement, by Major Gibb ....... .

Kew Brunswick boundary ...........•..•••••••••. {

Newfoundland storehouses; rspid decay of girders ..... . N cw Zealand; report by Lieut. Colonel Collinson, RE ..

Do. military operations do. Do. continuation of do. do.

Observatory formed of scaling ladders at Chatham in 1857 Officers of Engineers; syllabus of studies and duties ... . Ovens employed at ,v oolmer Camp ........ , .. , ..... .

Parapets; firing against parapets at Juliers .......... . Parapets; form of superior slopes, by General Portlock . . Q.

Pan pet breached with shells at Berlin .......•..•... Paris; description of the Forts . . . . . . . . . . . . . . . . . . • . Q.

Payerne's diving apparatus ......................... . Pei-Ho Forts; attack in 1859 ...•....

C. P. C. P.

III. IV.

YU. C. P.

III. IY.

nr. nr. IX.

X. VIII.

V.

IX. Y.

IX.

PAGB

73

139 1.59 80

186 222

68

64

64

419

66

70 230

238

1:15

389

5

22

H 130

IJ

159

33 H

35 51

CONTENTS OF VOLUMES.

Penetration of shot and bullets; experiments at Chatham in 1852 . . . . • •••• , ....•...... , ....•.

Penetration of rifle-bullets ; experiments at Chatham in 1858 .................................... ,

Phoonix Park, Dublin ; mining operations . . . • • ••.•.• Photography; notes by Captain Schaw.. .. .. . ........

Photo-zincography, described by Sir H. James •.•.•••• Pierriers; experiments at Chatham in 1853 . ....•.... .. Piles ; screw-piles used to anchor brushwood to protect

banks of rivers, &c. . • . . . . . • . . . . . . . . . . . . . • • • . .. Plates of wrought iron; practice against them in 1846 .. J>Intfortns; notes on construction, by General Portlock ..

Do. traversing plat.forms at Aden . . . ••••••••. • Do. Alderson's ......•......... , •••••..•.....

Plymouth; account of the siege in 1643 ............. . Polygonal fortification; memoir by Captain ~fangin ... . Pontoons; suggestions for their improvement, by Captain

Fo\vke, R.E. . . . . • . . . . . . . . . . . • . . • . . . .•••...... Portland; experiments in firing at a wall with 68-pr. shot

Portsmouth Dockyard; works executed by Colonel Sir H. Ja.mes, R.E ................. .. .............. .

Protractor used by United States Topographical Engineers

Pump to resist frost, in barracks at Quebec .•....•.....

Quarrying rock at Holyhead in 1850.. . . . . . ... . . . . .. . Do. do. in 1857.

Do. do. in 1860 .............. . .. .

Quebec i account of the operations in 1759 ....... , ... ,

Quebec and Halifax railway; report by Colonel Robinson

Q.

Q.

Q. Q.

TOL,

IV.

vu. C. P.

IX. x.

IV.

VII. V.

VIII. C. P. VIII.

IX. III.

VII. IX.

Ill. VIII.

IX.

II. VI. X.

C. P. II.

x.i.

PAGE

87

155 186 108 129

80

34

65 7

199 25

i5 167

81 1

77 196 82

140 28

1 31

xii. CONTENTS OF VOLUMES,

Raft-bridge across the harbour of Sebastopol ......... . Do. across the Danube ncnr Galatz ....... .

Railway from Quebec to Halifax; report by Col. Robinson Railways; construction; by l\lr. Dempsey ••........

Do. continuation of do . . . . . . . ..•.....•..•••. Railway survey in Ceylon in 18J7 ................ . Reports; on the composition of reports, by Col.Ndson, R.E. Revetments i remarks by Colonel Harness, R.E ...•...•

Do. do. by General Fanshawe, R.E ..

Do. do. by Sir William Denison, R.E. Do. do. by Sir John Burgoyne ....... Do. do. failure of one at Fort Elson ....••

Rheostat; ,vheatstone's impro\'ed by Becker ...... .

Rifles; experiments on penetration of bullets at Chatham

in 1858 ................................... ·-Rifled ordnance; breaching powers .... . Rivers; diversion of the course of rivers by means of

brush,vood ................................... . Road•making in Ceylon, by Captain Scbaw, R.E ....•.• Rochester Bridge landing stage ..... . Rochester Old Bridge; <lemolitiou in 18.j6.7

Do. do. in 1857 Do. do. in 1868

VOL.

VIII. VIII.

II. Q. YIU. Q. IX.

VII. VII.

I. C. P. C. P.

lll. IX. IX.

VII. X.

VII. VI.

VIII. VII.

VIII. IX.

PAGE

84

132 3!

85 156

8 73

119 68

402

154 64 73

155 1

34 121

62

1 63 39

Roofs; carpentry applied to roofs, by General Waddington Q. X. 71

Do. equilibrium of, by Lieutenant St. John, R.E. I. 21

Do. on Syrian cylinder roofs . . . . . . . . . . . . . • C. P. 34

Do. for building slips at Pembroke . . . . . . . . . . Q. IX. 50

Do. do. at Portsmouth. . . . . . . . . . . . . . . I,!. IX. 59

Rope stretched at Corfu for transport of materials . . . . . . IV. 65

Ruttunghur; demolition of fort in 1858 . . . . . . . . . . . IX. 7

Rutmoo river; dhiersion of its course by means of

brushwood . .. . . . . . . . . .. . .. .. . .. . .. .. . .. . . VII. 34

Cv)i'fl~TS OF YULUME:)

Saint LuC'ia; map executed by order of Sfr ,v. Reid Sant£\ Mauraj cyclopean walls, by General Portlock, R.E. Sapping-improvements suggested by Major Porter, R.E.

Scarp-wall at Fort Elson; failure ...........•........ Scaling ladders formed into an obsenatory nt Chatham

in 1857 . ...... ... .

Schweidnitzi account of mining operations at siege in 1762 Screw-piles; use in anchoring brushwood to protect banks

of rivers • • • • . . . . . • . . . . . . . . . . . ........•.... Seaford C]iff j mining operations in 1850 ....• ... Sebastopol j remarks on the Journal of the Siege, by Sir

J. Burgoyne . . . .. . ........... .... ... ........• Sebnstopol i report of Siege Record Board ...•.•••••••••

Do. demolition of docks by British .•.....•.... Do. do. by French Do. raft-bridge across the harbour . Do. demolition of ,vhite Barracks Do. Do.

demolition of Fort Nicholas by the French. account of works on the north side of the

harbour ...........••.... , .•.......... Shells exploded at Chatham in 1853 ........... . Shorncliffe; supply of water in 1855 ......... . Sicily; works constructed iu 18101 by General Lewis ... Siege operations ; on the preponclerance of the attack, by

General Lewis •.......... Siege operations at Chatham in 1848. . .. ... .... .

Do. ancient, by Captain Yule, B.E .. ...... . Siege operations at Juliers in 1860 ................... . Silistria; account of mining operations at siege in 1829.

Do. notes on the siege in 1854 . Slopes of earthen works in fortifications ............ .•

Smoke in casemates; experiments at Cliff-end Fort . .. Do. do. at Chatham and NeufBrisack Do. do. at Dover in 1859 ..

Smoky chimneys cured by Major Hassard, R.E ..•..... , Sobraon; intrenchments constructed by the Sikhs •.....

YOL,

Q. X. C. P. C. P.

IX.

Vil. VII.

VII. I.

IX. VI. VI. VI.

VIII. VI.

VII.

VII. IV. v.

III.

VI. C. P . Ill.

X. VII.

V. x.

IX. V.

IX. VII.

Do. plan of battle . . . . . . . . . . . . . . . . . . . . . . . . . . . . Q.

I. X.

VI. Specific gravity of the earth, by Sir H. James, R.E ..... Sphere; geometrical projection, by do. Stabling at Aldershot for temporary purposes ....•... ..

VII. VII.

~iii.

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75 160

110 217 128

159 65

167 126

46 39 13

137 24

156 149 134 88

XL\", CONTENTS OF VOLUMES.

Stockade; demolition at Chatham in 1848

Do. <lo. in 18J6-7 ......... .. . Stone-mo1tnrs; experiments at Chatham in 1853 ... .

Storms on the Atlantic; notes by Colonel Alexander, R.E.

Su,.,.ey for canal from Bay of Fundy to Gulph of St.

Lawrence ......• .. .....•.•••.•...•••...•••. , Su1Tey; Ordnance; sketch of origin and progress . .... . Sur-rey for railway in Ceylon ................... . Survey by Mr. Hemming at Ca.pe of Good Hope ....... .

Sutlej campaign in 1845-6 ........•..• ,. ••.••.•.••.

Taku Forts; attack in 1859 ....... ........ . ....... .. Tanks lined with lead .•..........•.••.............. Tanks at Vida; account of the percolators .••••......... Tantamar marshes; report on reclamation, by Colonel

Crawley ............................... .. .. .. Tapia; construction of buildings at Gibraltar ••••••.... Telegraph Atlantic cable laid in 1857 ............. . Tide in Lake Michigan observed by Lieutenant Colonel

Graham, U.S.E ...•......................•.•.•.• Tien-tsin River; attack of Forts in 1859 , ..••••.••...•

Traversing platforms at Aden .... , .................. . Trench-cavalier demolished at Chatham in 1855 ... . Turkey; topographical notes • • . . .. • . ........... . Tutteah; demolition of fort. • . . . . ..•...•.•...•..• _ ..

YOL.

C.- P. IV. IV. III.

Q. VIII. III. IV.

VII. I.

Q. X.

IX. IX.

C. P.

Q. VIII. X.

VII.

X. IX.

C. P. V.

IV. VIII.

PA&E

221 51 80

196

186 V.

8 27

1&6

51 47 23

!Se

25 99

121 51

199 63

105

54

CONTEXTS OF VOLUMES.

Vido; account of percolators at the tanks ....... . Voltaic battery; its employment in firing charges, by

Cnptain H Scott ............................. . \'o!taic battery i application of it, by Captain "·ard, R.E.

"·all pieces ;-penetration at Julicrs ....••• , ....... . "alls at St. l\laura of cyclopean construction .....•.... \Vs.ter contaminated with lead ...........•.......... Wnter-supply for cnmp at Shorncliffe ............. . "'ater-wbeel, and water-course at \Vnltham Abbey ""ans i theory of their movement and action, by General

Cole............ . . .......•........ ,veights; mode of carrying them with poles in China ,v1.:ights; mode of lifting weights at Hong-Kong ... , . ,vindow fastenings at Pisa . . . . . . . . • . . • • . . . . . . . \Vood; protection of wood against fire, by l\Ir. Abel ...

YOL.

c.!'.

YI. ff.

x. C. P.

IX. Y.

Q. IX.

IV. C. P.

Q. X. Q. X.

V.

l'Rt'..TED BY W. P, JACKSON, LIBRARY, WOOLWICH,

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